True Televisions have the CRT Tube !!
Welcome to the Obsolete Technology Tellye Web Museum. Here you will see a TV Museum showing many Old Tube Television sets
all with the CRT Tube, B/W ,color, Digital, and 100HZ Scan rate, Tubes technology. This is the opportunity on the WEB to see, one more time, what real technology WAS ! In the mean time watch some crappy lcd picture around shop centers (but don't buy them, or money lost, they're already broken when new) !!!

Richtige Fernseher haben Röhren!

Richtige Fernseher haben Röhren!

In Brief: On this site you will find pictures and information about some of the electronic, electrical and electrotechnical technology relics that the Frank Sharp Private museum has accumulated over the years .

Premise: There are lots of vintage electrical and electronic items that have not survived well or even completely disappeared and forgotten.

Or are not being collected nowadays in proportion to their significance or prevalence in their heyday, this is bad and the main part of the death land. The heavy, ugly sarcophagus; models with few endearing qualities, devices that have some over-riding disadvantage to ownership such as heavy weight,toxicity or inflated value when dismantled, tend to be under-represented by all but the most comprehensive collections and museums. They get relegated to the bottom of the wants list, derided as 'more trouble than they are worth', or just forgotten entirely. As a result, I started to notice gaps in the current representation of the history of electronic and electrical technology to the interested member of the public.

Following this idea around a bit, convinced me that a collection of the peculiar alone could not hope to survive on its own merits, but a museum that gave equal display space to the popular and the unpopular, would bring things to the attention of the average person that he has previously passed by or been shielded from. It's a matter of culture. From this, the Obsolete Technology Tellye Web Museum concept developed and all my other things too. It's an open platform for all electrical Electronic TV technology to have its few, but NOT last, moments of fame in a working, hand-on environment. We'll never own Colossus or Faraday's first transformer, but I can show things that you can't see at the Science Museum, and let you play with things that the Smithsonian can't allow people to touch, because my remit is different.

There was a society once that was the polar opposite of our disposable, junk society. A whole nation was built on the idea of placing quality before quantity in all things. The goal was not “more and newer,” but “better and higher" .This attitude was reflected not only in the manufacturing of material goods, but also in the realms of art and architecture, as well as in the social fabric of everyday life. The goal was for each new cohort of children to stand on a higher level than the preceding cohort: they were to be healthier, stronger, more intelligent, and more vibrant in every way.

The society that prioritized human, social and material quality is a Winner. Truly, it is the high point of all Western civilization. Consequently, its defeat meant the defeat of civilization itself.

Today, the West is headed for the abyss. For the ultimate fate of our disposable society is for that society itself to be disposed of. And this will happen sooner, rather than later.

OLD, but ORIGINAL, Well made, Funny, Not remotely controlled............. and not Made in CHINA.

How to use the site:

- If you landed here via any Search Engine, you will get what you searched for and you can search more using the search this blog feature provided by Google. You can visit more posts scrolling the left blog archive of all posts of the month/year,or you can click on the main photo-page to start from the main page. Doing so it starts from the most recent post to the older post simple clicking on the Older Post button on the bottom of each page after reading , post after post.

You can even visit all posts, time to time, when reaching the bottom end of each page and click on the Older Post button.

- If you arrived here at the main page via bookmark you can visit all the site scrolling the left blog archive of all posts of the month/year pointing were you want , or more simple You can even visit all blog posts, from newer to older, clicking at the end of each bottom page on the Older Post button.So you can see all the blog/site content surfing all pages in it.

- The search this blog feature provided by Google is a real search engine. If you're pointing particular things it will search IT for you; or you can place a brand name in the search query at your choice and visit all results page by page. It's useful since the content of the site is very large.

Note that if you don't find what you searched for, try it after a period of time; the site is a never ending job !

Every CRT Television saved let revive knowledge, thoughts, moments of the past life which will never return again.........

Many contemporary "televisions" (more correctly named as displays) would not have this level of staying power, many would ware out or require major services within just five years or less and of course, there is that perennial bug bear of planned obsolescence where components are deliberately designed to fail and, or manufactured with limited edition specificities..... and without considering........picture......sound........quality........

Tuesday, September 27, 2011

PHILIPS 20AX SYSTEM:The 20AX system was introduced in Europe as the first self converging picture tube/deflection coil, combination for 110° degree deflection and screen sizes up to 26". The system is based on the automatic convergence principle discovered by Haantjes and Lubben of Philips Research Laboratory more than 35 years ago. It makes use of an in-line gun array in conjunction with a specially designed saddle type deflection coil. Residual small tolerance errors are compensated by a simple dynamic four-pole system. The tube is 2 cm shorter than conventional 110Â°tubes and has a standard 36.5 mm neck in order to obtain good color selection. A slotted mask is used in combination with a stripe-structure screen. Picture sharpness is ensured by an astigmatic electron gun.

Sectionally wound saddle coils are used, and the shells in which they are mounted incorporate reference pieces to minimize assembly tolerances. An easy to operate assembly of multi-pole magnet rings provides for static convergence, color purity, and raster symmetry adjustment.

INTRODUCTIONSince the invention of the siiaciowmasir, picture tubedevelopment has revolved almost exclusively around thedelta-gun configuration. Refinement of this technologyhas resulted in extremely high quality colour reproductionwhich has fully justified the effort expended in itsperfection. In recent years, however, several manufacturers have been investigating the possibilities of simplifyingthe conventional receiver. In particular, a great deal ofresearch has been carried out on picture tubes incor-porating in-line gun arrays. The main advantage offeredby such a gun configuration compared with the conventional delta-gun array is that dynamic convergenceUDC 621. 397. 132

2OAX receiver compared with the I5 to 18 intricateenergy-consuming corrections necessary in a comparabledelta-gun set.Colour selection is achieved by means of a verticallyslotted shadowmask, the phosphors being deposited onthe screen in vertical stripes. The tube has a standard36‘5mm neck, but because of modifications to the gunmade possible by the elimination of pole pieces required for dynamic convergence corrections, the necklength is reduced by 20mm compared with its delta-gunequivalent.This article describes briefly the theory behind 20AX,and gives details of the picture tube and deflection coilcorrections can at least be simplibed, and at best,eliminated completely.

The 2OAX system adopted by Mullard and introducedearly in 1974, is the first inherently self-converging110° colour television system capable of use withscreen sizes up to 26in. lt incorporates a horizontalline gun array with a specially designed saddle-wounddeflection yoke. The complex dynamic convergencecorrection clreulm required by delta-gun receivers areeliminated. The only dynamic corrections required in20AX are those to compensate for small residualmanufacturing tolerances. These are few, and relatively straight-forward. In fact, only 7 simple dynamic corrections expending virtually no energy are required in a

CONVERGENCE AND DEFLECTION'ln any colour television picture tube, the three electronbeams are deflected by a common deflection field. Thisfield not only deflects the beams but to some extentdefocuses them, hence giving rise to convergence errors.The theory behind convergence errors caused by deflection fields has been covered in detail in a previousarticle (Ref. 1). For completeness, however, a simplifieddescription ol' the theory is given here.Consider a conical pencil of beams which, in theabsence of a deflecting field, converges at the centre of thescreen (see Fig. 1). From the behaviour of such a beampencil in a deflection field. conclusions can be drawnabout the behaviour of the three beams in a delta-gunpicture tube.

MisconvergenceThe main characteristics of a deflection field thatdetermine its convergence properties are curvature of theimage field, astigmatism, and coma.Curvature of the image field results in the radius ofcurvature of the surface swept by the convergence pointof the beam pencil being lesithan that of the screen(see Fig. 2). On a ilat screen, the image of the beampencil is circular. Considering the three beams for a delta-gun as elements of a beam pencil, it is seen in Fig. 3that the convergence point on a flat screen forms anequilateral triangle.The second characteristic, astigmatism, causes theconvergence point of the beam pencil to separate intotwo focal lines, one parallel to, and one perpendicularto, the direction of deflection. One of these focal lineslies in front of the original convergence point, and theother behind it. The combined result of astigmatism andcurvature of field on the three beams of a delta-gun tubeis shown in Fig. 4. The image spots now form isoscelestriangles, instead of the equilateral triangles resultingfrom curvature of field only. Fig. 5 shows how curvaturerequired, the complexity of the circuits increasing withincreasing angle of deflection. For 110° deflection, 15to 18 adjustments are normally necessary.

PRINCIPLE OF SELF-CONVERGENCE AND 20AXAs early as 1954, Haantjes and Lubben (Ref. 2) showedthat it would be possible to eliminate convergenceerrors by adopting an in-line gun array in conjunctionwith a specially designed deflection assembly.Their solution to the convergence problem was basedon the finding that curvature of field could be compensated by increasing the astigmatism of the deflectionlield in such a way as to eliminate misconvergence in,say, the horizontal direction at the cost of increasing itin the vertical direction. In a delta-gun tube the effect ofthis would be to make the vertical focal line in Fig. 4coincide with the flat screen over all angles of dellection.lf the gun array is horizontal-in-line, however, thisvertical focal line degenerates to a point, resulting inperfect convergence at all positions on the screen (seeFig. 7).lf the vertical deflection field were identical to thehorizontal deflection field, but rotated through 90°, thehorizontal focal line would coincide with the screen atall points, not the vertical one as required. The positionsof these focal lines therefore need to be reversed. This isachieved by reversing the sign of the vertical deflectionfield with respect to the horizontal field. Thus, thevertical focal ‘lines’ (effectively points) produced byboth fields will coincide with the screen at all angles ofdeflection, giving automatic convergence.In a system with in-line guns, coma caused byhorizontal deflection shifts the centre beam horizontallywith respect to the outer beams, and coma caused byvertical deflection shifts the centre beam vertically(see Fig. 8). Thee field distribution must therefore bearranged in such a way as to virtually eliminate the comaerrors shown in Fig. 8. This has been achieved in the20AX system.To produce the automatic convergence required, the horizontal deflectionfield must .be pincushion-shaped and the vertical deflection field must be barrel-shaped, in the parts of thefield close to the screen.

Coma is affected by the distribution in both parts ofthe field. One way of minimising it would be to makethe field homogeneous throughout, but this would conflict with the astigmatism requirement. An alternative way, the one adopted in 2OAX, is to design thehorizontal and vertical fields so that the coma contributions in each part cancel; that is, if the field is pincushion-shape in one part of either field, it must bebarrel-shape in the other part (see Fig.l0).

COIL DESIGNThe main aspects of coil design that must be consideredBIOS

1) the shape of the coil to give the required fielddistribution;2) the provisions necessary for ensuring precise reproducibility in manufacture.Choice of coil geometryFor 2OAX, two deflection system configurations wereconsidered:

1) toroidal coils for both horizontal and vertical deflection,2) saddle coils for both horizontal and verticaldeflection.At first sight, the toroidal system appears to lenditself to more precise manufacture. Fewer turns arerequired, and each of them can be located precisely byannular combs at both ends of the ferrite ring. Thematerial content is low and manufacture can be easilymechaqised.However, for all its apparent simplicity, the toroidalyoke does have important limitations. -1) Because of the small mimber of tums, the impedanceis low; the large stray field impairs deflectionsensitivity and tends to cause interference in nearbycircuitry.2) Strong coupling between the horizontal and vertical deflection colls makes it difficult to usedifferencecurrent drive (see later) for tolerancecompensation.3) in most toroidal yokes, turns have to be layered inat least part of the winding, and this tends todegrade precision.But the most fundamental drawback is that design freedom is severely restricted. Other than the shape of the core, the only design parameter is the angular positioning.

Required field distributionAstigmatism and coma both depend on the distributionofthe deflection iield. For a qualitative discussion of thisdependence, the field can be considered in two parts, onepart close to the guns, and the other close to the screen.Astigmatisrn is influenced mainly by that patt of theHeld close to the screen. If the field distribution is homogeneous (sec Fig. 9), astigmatism is approximately zero.Barrel-type distribution and pincushion-type distribution

To produce the field distribution required for the20AXselt1convergingsystem, angle c: must vary along thelength ofthe deflection coil. For the horizontal deflectioncoil, oc must increase from about 90° at the gun end toabout 150° at the screen end to avoid coma errors. Forthe vertical deflection coil, exactly the opposite variationis required; um is, irom 150° at the gun end to 90° atthe screen end.This simple description considers only the lower orderterms in the equations describing the Held produced by asymmetrical pair of single-turn However,undesirable effects due to large, higher-order terms canbe minimised by adding more turns to each winding andcarefully defining their positions. The final coil design for20AX employs a relatively large number of turnsaccurately distributed around the inside of the ferritecore. The distribution varies along each coil in such away as to provide the required astigmatism and absenceof coma necessary to achieve optimum convergenceover the whole screen.

Coil manufactureThe manufacture of such coils in large quantities and tothe required accuracy presents certain difficulties. Coilsof complex shape can be wound on specially designed

The principle of sectional winding is to divide thecritical parts of each coil into as many sections as may beneeded to ensure the requisite precision, and to make thestarting point and number of turns in each sectioncompletely independent of those that have been woundbefore. This can be done by inserting spaced index pinsinto the winding jig as the coil takes shape. each pinserving to establish the starting point of a new section.The technique is of value not only in the manufacture ofclose-tolerance deflection coils but also in their designand development. Fig. 12 shows how the overallprecision error is reduced by sectional pin indexing.Table l gives the electrical specifications for the horizontal and vertical deflection coils. ln Fig. 13, the horizontal deflection coils are shown mounted in thedeflection yoke.

A cutaway view of the deflectionassembly is shown in Fig. 19. More details of deflection coil design and manufacture are given in Ref. l.

Fig. 14 - Schematic outline of ferrite core lside elevation)showing one of the field Shaper cut-outscoils are mounted in a split plastic shell which incorporates moulded-in locating pieces for each winding. Thissecures them in the correct position relative to the ferritering, regardless of small variations in tum distribution.The coils and ferrite ring are mounted as an adjustableunit in a housing (Figs. 15 and 19) that clamps to theneck of the tube and engages a centring ridgernouldedinto the cone. Only two adjustments are provided: a:t 7° rotation for raster alignment, and a 6mm axial shiftfor colour purity. Clamps on the housing lock the unit inthe desired position. The axial movement is provided by

In comparison with a delta-gun system, the deflectionfields required in a self-converging in-line system givegreater pincushion E-W raster distortion but less N-Sdistortion. Because of the sign of the astigmatism, theN-S distortion is barrel-shaped. N»S raster distortion canbe decreased still further by treating the shape of theferrite ring as an additional design parameter. In the `20AXdeflection unit, shaped cut-outs (Fig. 14) at the gun endof the ferrite ring are positioned so that they affect onlythe vertical deflection field, giving a N-S raster shapewhich is fully acceptable without further correction. TheE-W raster distortion of 13% is corrected by means ofconventional deflection current modulating circuitry.

Mechanical assemblyln addition to the measures taken to achieve the highestpossible precision in the manufacture of the deflectioncoils. special attention is also paid to their assembly. Thean adjustable ring at the back of the housing, the coilmoving in a helical slot in the circumference.

Static corrections'Il1e static correction assembly (Figs. 16 and 19) consistsof four ring-shaped permanent magnets; one for colourpurity, one for raster symmetry, and two for staticconvergence adjustments. lt is located on the neck of thetube between the gun and the deflection yoke. Eachelement of the assembly comprises a pair of magnetisedplasto-ferrite rings coupled by pinion gears (Fig. 17). Byrotating both rings in the sarne direction, the field isrotated; by rotating them equally in opposite directionsthe lield strength is altered.One pair of rings, magnetised as a vertical two-polemagnet, adjusts colour purity in the horizontal direction.

Another pair, magnetised as a horizontal two-pole magnet,corrects any vertical misalignment there may be betweenthe beams and the axis of the tube-yoke system. Owingto the strong astigmatism of the horizontal deflectionHeld, such misalignment would otherwise cause curvatureof the horizontal axis of the raster. Two pairs of ringsallow for static convergence correction, one magnetisedas a four-pole magnet, and the other as a six-pole magnet.Adjustment of the four-pole pair pre-deilects the twoouter beams equally in opposite directions, and adjustment of the six-pole pair pre~deflects them equally in thesame direction, making it possible to bring all three beamspots into coincidence on the screen.'Ihe complete multi-pole static correction assemblyfits flush with the rear of the deflection coil housing onthe neck of the tube (see Fig. 19). It is located by a keyand slot in the housing, and is locked by a finger-operatedclamp on the multi-pole unit.

20AX PICTURE TUBEExternally there is little to distinguish a 20AX picturetube (Fig. 18) from a comparable delta-gun 110° typeapart from the shorter neck and the deflection yokeeentring ridge on the cone. lntemally, however, thereare fundamental differences. A cutaway view ofa 20AXpicture tube, deflection yoke, and static correctionassembly is shown in Fig. 19.

Electron gunThe electron guns are mounted side by side, the twoouter guns (red and blue) being slightly inclined towardsthe centre gun (green). The green beam is positionedbetween the other two to reduce the effect of smallresidual convergence errors. (The eye is more sensitive toconvergence errors between red and green, or blue. andgreen, than between red and blue.) The cathode of eachgun is of the Quick-vision type with low thermal capacityand improved heater-to-cathode heat transfer, giving a70% reduction in the time from switch-on to the appearance of a picture. It is thus possible to obtain a picturewithin S seconds of switch-on.Elimination of the pole shoes (normally required fordynamic convergence) at the muzzle end of the gun,together with a slight reduction in gun length,'enablesthe length of the tube neck to be reduced by 20mm.Improved precision in gun manufacture and assemblyhas narrowed the spread in the position ofthe staticallyconverged beams with respect to the screen centre,thus allowing shift compensation circuits to be dispensedwith.An important aspect of the design of theelectron gunis its relation to picture definition. ln a conventionaldelta-gun tube, over-focusing of the beam occurs in thedeflection field. This means that a spot that is in focus atthe centre of the screen appears as a blurred spot with abright core at the edge of the screen (see Fig. 20a). In aself-converging system, however, the deflection field notonly fields automatic convergence for beams in thehorizontal plane but also automatically focuses allelectron rays in a horizontal cross-section through eachbeam. This means that the horizontal cross-section of theelectron spot is automatically focused over the entirescreen, so that horizontal haze is eliminated, althoughfor fundamental reasons the spot size increases duringdeflection. On the other hand, the vertical cross-sectionof the beam is subjected to a much stronger over-focusing action in a self-converging field than in a conventional field. These two factors result in a narrowhorizontally-elongated spot with pronounced verticalhaze (see Fig. 20b).To counteract this deflection defocusing, the electronguns are designed to give astigmatic beams. This is achievedby introducing a plate with a horizontal slit in the secondgrid to reduce the height of the beam in the deflectionfield. This considerably reduces the vertical haze (see Fig.20c), but results in a slightly larger spot at the centre ofthe screen. One advantage of the larger spot, however, isthat moiré effects are reduced. (Moiré effects are furthersuppressed by suitable design of the shadowmask; seelater.)

Although reducing the height of the beam increasesits width, there are no adverse consequences-because ofthe automatic focusing of the horizontal Held. On thecontrary, at the centre of the screen the width of thespot size is reduced because of the decreased space chargeeffect, and this also applies during deflection.As discussed earlier, the 2OAX field is free from coma.If there were coma errors, however, additional defocusingof the outer beams during deflection will occur. The useof lleld shapers for correcting coma errors cannot correctspot distortion resulting from the same error. This is anadditional reason for adopting a coma-free deflectionsystem for 20AX.

Shadowmask and screenLike most other tubes with in-line guns, the 20AXpicture tube has a screen consisting of vertical phosphorstripes. Colour selection is achieved with a verticallyslotted shadowmask (see Fig. 19). Thus colour purity ismade independent of beam landing in the verticaldirection. However, to obtain the same apparent fmenessin the structure of the picture as is'obtalned with deltagun tubes, the horizontal spacing between stripes of thesame colour in adjacent triads must be about equal to thehorizontal spacing between vertical rows of dots of thesame colour on a conventional screen (see Fig. 21). Thismeans that the width of each colour stripe must be equalto about half the diameter of a conventional phosphordot. Therefore, the absolute value of the horizontalreserve, assuming equal mask transmission, is abouthalved. This disadvantage must be weighed against theunlimited vertical landing reserve. However, anotheradvantage of vertical stripes is that the landing reserve isnot reduced by triad distortion. In fact, the tube ismanufactured so that the centres of the electron spotscoincide with the centres of the phosphor stripes. If themask is heated by electron bombardment in the brightareas of the picture, the resulting landing shift willcause the red beam to land partly on the blue phosphor,the green beam partly on the red phosphor, and theblue beam partly on the green phosphor. However,white still remain white. This is, of course,strictly true only for a current ratio of l : l : 1 andidealised geometrical conditions, but even under otherconditions, the advantage is still noticeable.In the 26in 20AX picture tube, the centre-to-centrespacing of the phosphor stripes is 26Snm, and the centre-to-centre spacing of adjacent triads, 79Sym. Each slot ofthe shadowmask corresponds to one triad. To accommo-date the spherical contour of the mask, the slots arebridged at regular intervals throughout their length. inthe interests of suppressing moire' effects, a bridginginterval of 8l0pm (as projected on the screen) is used; inthe interests of maximum strength and stability, thebridges are staggered by half an interval from slot to slot.Use of the standard 36°5mrn neck diameter enablesthe electron guns to be spaced for optimum colourselection. Adjustment of colour purity requires a horizontal displacement of the three beams of no more than45nm. No vertical adjustment is required.

DegaussingLike most 110° picture tubes on the European market,the 20AX picture tube uses an internal magnetic shield.Advantage has been taken ofthe unlimited vertical landingreserve inherent in the 20AX system by rotating tl1edegaussing coils through 90° (Fig. 22). By this means, thevertical component of residual magnetic flelds that causehorizontal landing errors is oomple tely eliminated. Becausethe mask material is not interrupted by holes in thedirection of the degaussing field lines (see Fig. 23), themagnetomotive force can be smaller. Therefore the number of ampere-turns in the degaussing coils has beenreduced from S00 to 300, resulting in a 60% saving ofcopper wire compared with conventional 110° tubes.

To eliminate the risk of mis-landing caused bycurrents inducedin the degaussing coils by the horizontaldeflection lield, the degaussing coils are short-circuitedat horizontal deflection frequencies by a 0- l,uF .capacitorExcept for this additional capacitor, the degaussingcircuit (see Fig. 24) is the same as is used with a Phase llll0° picture tube.

TOLERANCE COMPENSATIONAlthough 20AX is inherently a self-converging system,some dynamic correction may be required to compensatefor small manufacturing tolerances. The system can beexplained as follows.Fig 25 shows a situation in which the plane where .thebeams are converged automatically is slightly tilted withrespect to the screen plane because of some small leftright asymmetry in the distribution of the horizontaldeflection field. As a result, horizontal convergenceerrors of opposite sign appear at the sides of the screen.The same type of error can be caused by a horizontaldeviation of the undcflected beams from the screencentre. These errors can be corrected by a four-polefield aligned diagonally with respect to the deflectionfields. This field is generated by four windings aroundthe core of the deflection yoke. The windings must bedriven by a sawtooth current which can be obtaineddirectly from the horizontal dcllection circuit.In the same way, top»to-bottom asymmetry of thevertical deflection field, or a vertical deviation of theundetlected beams from the screen centre, causeshorizontal convergence errors at the top and bottom ofthe screen. These errors can be corrected by passing sawtooth currents at vertical deflection frequency throughthe four-pole windings.Horizontal displacement of the electron beams withrespect to the deflection coil centre is not normallydetrimental, because the system automatically convergesall the beams which lie in a horizontal plane throughthe same time, however, vertical convergence errors willappear during horizontal deflection and will cause crossover of the horizontal red and blue lines (see Fig. 27).The same type of error can also be caused by top-to bottom asymmetry of the horizontal deflection field.These errors can be corrected by a four-pole fieldwhich is aligned orthogonally with respect to the deflection iields. This type of four-pole field can be generatedby unbalancing the current through the halves of thehorizontal deflection coil. Similarly, left-to»rightasymmetry of the vertical deflection field. or horizontaldeviation of the undeflected beams from the screencentre, causes vertical convergence errors during verticaldeflection (see Fig. 28). These errors can be correctedby unbalancing the current through the halves of thevertical deflection coil.lf the plane of the beams is rotated with respect to thenormal orientation, a parabolic vertical convergence errorwill occur during both horizontal and vertical deflection(see Fig. 29). This error can also be corrected by unbalancing the current through the halves of the dc-flection coil. ln this case, however, the superimposedcorrection current must be parabolic.The six corrections so far mentioned apply to 22inpicture tubes; they are two horizontal sawtooth corrections, two vertical sawtooth corrections, and two verticalparabola corrections. For the 22in and 26in versions ofthe 20AX tube, small systematic parabolic horizontalcorrection component has to be added during verticaldeflection. For these screen sizes, there are thereforeseven corrections.

Advantages of the four-pole systemThe errors which require correction are very small(maximum distance between the outer beams in mostcases is of the order of 2mm}. The corrections thereforeneed not be very accurate, and simple circuits can beused. 1% pole shoes cr separate ccrrectirin units are neededAs the corrections are made in the deflection plane, theydo not affect colour purity. The method of applyingcorrections in the 2OAX system has the advantage thatthe number of corrections can be reduced, withoutchanging the system, as manufacturing tolerances arereduced.

Cathode-ray tube for displaying coloured pictures PHILIPS IN-LINE ELECTRON GUN SYSTEM TECHNOLOGY:
A television display tube of the shadow-mask type, comprising three electron guns having parallel axes; the last electrode of each electron gun has the shape of a cylindrical sleeve and the electron gun the axis of which do not coincide with the main axis of the tube have an eccentric last electrode.

1. A cathode-ray tube for displaying color pictures comprising in an evacuated envelope: three electron guns the axes of which are parallel to the main axis of the tube for producing three electron beams, a color selection electrode comprising a multitude of apertures, a display screen having three patterns of regions luminescing in different colors, means for converging the three electron beams so that they intersect each other near the color selection electrode, each of said electron beams being assigned to one of the said patterns by means of the color selection electrode, each of said electron guns comprising a set of successively arranged electrodes including at least a cathode, a control grid, an anode and an additional last electrode which has the form of a substantially cylindrical sleeve, at least two electron guns having respectively, a center axis which is eccentric relative to the main axis of the tube, the last electrode of each of said two eccentric electron guns having a center axis which is eccentric relative to the center axis of the assigned electron gun in a plane through the main axis of the tube and the center axis of the assigned electron gun and at a larger distance from the main axis of the tube than is the axis of the assigned electron gun, and said last electrode having an inner diameter which is larger than the largest inner diameter of any other electrode of the assigned electron gun.

2. A cathode-ray tube as claimed in claim 1, having three electron guns the axes of which are in one plane and the center axis of one gun inclusive said last electrode coincides with the main axis of the tube.

3. A cathode-ray tube as claimed in claim 1 and having three electron guns in a triangular arrangement, wherein the last electrodes of the three electron guns have the same inner diameter.

4. A cathode-ray tube as claimed in claim 1, wherein the inner diameter of the last electrode assigned to each of the two eccentric electron guns is equal at least to the largest inner diameter of the corresponding electron gun increased by twice the distance between the axes of the last electrode and the electron gun.

Description:

The invention relates to a cathode-ray tube for displaying color pictures and comprising in an evacuated envelope: three electron guns the axes of which are parallel to the main axis of the tube for producing three electron beams, a color selection electrode comprising a multitude of apertures, a display screen having three patterns of regions luminescing in different colors, and means for converging the three electron beams so that they intersect each other near the color selection electrode, which electron beams each are assigned to one of the said patterns by means of the color selection electrode, which electron guns each comprise at least a cathode, a control grid and an anode and furthermore a last electrode taken from the cathode which has the form of a mainly cylindrical sleeve, at least two of the said electron guns having an axis which is ecentric relative to the main axis of the tube.

Such a cathode-ray tube is known from the U.S. Pat. No. 3,011,090. In order to converge the three electron beams so that they intersect each other near the color selection electrode it is furthermore known to cause the axes of the three electron guns to intersect each other in a point in the center of the colour selection electrode. The said U.S. patent states as a drawback of this that the guns have to be positioned very accurately in the tube. Another drawback is that the electrodes of the three guns are assembled on three assembling pins which thus have to enclose a very accurely determined angle relative to each other. In order to be able to subsequently remove the set of three assembled electron guns from the three assembly pins, it is necessary for said pins to be secured in a jig so as to be detachable, as a result of which their mutual angle becomes less accurate due to detrition.

It is the object of the invention to mitigate the said drawbacks and the invention furthermore provides a very simple construction for converging three electron beams from three assembled electron guns which operate independently of each other and the axes of which are parallel.

According to the invention, a cathode-ray tube of the type mentioned in the preamble is characterized in that the last electrode of each electron gun which is eccentric relative to the main axis of the tube has an axis which is eccentric relative to the axis of the assigned electron gun in a plane passing through the main axis of the tube and the axis of the assigned electron gun and at a larger distance from the main axis of the tube than the axis of the electron gun and that the said last electrode has an inner diameter which is at least equal to the largest inner diameter of any other electrode of the electron gun increased by twice the distance between the axes of the last electrode and the electron gun.

Due to the eccentrically arranged last electrodes, convergence is obtained in a simple manner so that the axes of the three electron guns can be parallel and the assembly pins for assembling the three guns can be rigidly secured in a jig. By choosing the inner diameter in the stated manner to be larger it is achieved that the last electrode which is mounted first on the assembly pin can easily be moved over the thinner pin portions destined for the other electrodes, while the assembled gun can still removed from the pin because no reentrant pin portion is formed.

The invention relates in particular to such a cathode-ray tube having three electron guns the axes of which are in one plane and one axis coincides with the main axis of the tube which is characterized in that the axis of the last electrode of the electron gun the axis of which coincides with the main axis of the tube, coincides with the axis of the electron gun.

The invention also relates to a cathode-ray tube having three guns in a triangular arrangement which is characterized in that the last electrodes of the three electron guns have the same inner diameter.

The invention will be further described in greater detail with reference to the accompanying drawing, of which

FIG. 1 shows a cathode-ray tube according to the invention,

FIG. 2 shows the three electron guns of the tube of FIG. 1 in their mutual arrangement,

FIG. 3 shows the three electron guns of a known cathode-ray tube during assembly, and

FIG. 4 shows the three electron guns of a cathode-ray tube according to the invention during assembly.

The tube shown in FIG. 1 comprises in an evacuated glass envelope 1 a set of electron guns 2, a colour selection electrode 3 and a display screen 4. Outside the envelope 1 of the tube are shown a set of deflection coils 5 which serve for the deflection across the display screen 4 of the electron beams produced by the electron guns 2. In known manner, which need not be further explained, one of the electron beams impinges, via the apertures 6 in the colour selection electrode 3, only upon regions having red luminescing phosphor of the display screen 4, the second electron beam impinges only upon regions having green phosphor and the third electron beam impinges only upon regions having blue phosphor. The main axis of the tube is denoted by the reference numeral 7.

FIG. 2 shows the set of electron guns 2 in greater detail. It comprises three electron guns 10, 20 and 30, the axes 17, 27 and 37 of which are parallel to each other. The electron gun 10 comprises a cathode 12 having a filament 11, a control grid 13, and anode 14, a focusing electrode 15 and an accelerating electrode 16. The corresponding electrodes of the electron gun 20 are denoted by reference numerals 21 to 26. The corresponding electrodes of the electron gun 30 are denoted by reference numerals 31 to 36. In a manner not shown the electron guns 10, 20 and 30 are secured to glass supporting rods so as to be immovable relative to each other by means of connection lugs sealed in the supporting rods. As shown in FIG. 2, the axes 17, 27 and 37 of the electron guns are in one plane. In another embodiment which needs no further explanation the electron guns 10, 20 and 30 have a thriangular arrangement, that is to say that the points of intersection of the axes of the electron guns with a plane normal to the main axis of the tube form an equilateral triangle having the point of intersection of the main axis of the tube as center of gravity.

As shown in FIG. 2, the acceleration electrodes 16 and 36 have a slightly larger diameter than the focusing electrodes 15 and 35, while the axes 18 and 38 of the electrodes 16 and 36 are also eccentric relative to the axes 17 and 37. The electric field between the electrodes 15 and 16 and 35 and 36, respectively, thus has such a shape that the electron beams produced by the electron guns 10 and 30 are deflected towards the electron beam produced by the electron gun 20. The three beams intersect each other at the area of the colour selection electrode 3. In the case of three electron guns in a triangular arrangement, the electron beams are deflected towards each other in a quite analogous manner. The stated eccentricity is so small that the deviation from the rotational symmetry of the electric field between the electrodes 15 and 16 and 35 and 36, respectively, has a detrimental influence on the structure of the electron beams individually. The largest inner diameter of the electrodes 15, 25 and 35 is 7.6 mm. The inner diameter of the electrode 26 is also 7.6 mm. The inner diameter of the electrodes 16 and 36 is 8.2 mm. The eccentricity of the electrodes 16 and 36, that is to say the distance between the axes 17 and 18 and 37 and 38, respectively, is 0.3 mm. As already noted, the axes 27 and 28 coincides. In the case of three electron guns in a triangular arrangement, all the acceleration electrodes are eccentric relative to the corresponding focusing electrodes.

FIG. 3 shows three electron guns of a known cathode-ray tube during their assembly. Three assembly pins 41, 42 and 43 are secured in a block 40. The axes of the pins 41 and 43 intersect each other in a point on the axis of the pin 42. For clarity, the angle between the axes of the pins 41 and 42 and 42 and 43, respectively, is shown to be larger than is the case in practice. The diameter of the pins 41, 42 and 43 becomes smaller stepwise towards their end. FIG. 3 shows how this is used to assemble the electrodes of an electron gun on a pin. Temporarily provided spacing members 44 are also used. In FIG. 3, the electron gun on the pin 42 is still to be assembled. After providing all the electrodes, the electrodes which are provided with connection strips not shown are sealed in glass supporting rods by means of said strips. The three electron guns then form one assembly and it is obvious that, for being able to remove the pins 41, 42 and 43 from the guns, it is necessary first to remove the pins 41, 42 and 43 from the block 40, only after which they can be withdrawn from the guns. This requires a large number of operations and in addition produces detrition so that the angle between the pins 41, 42 and 43 becomes inacurate.

FIG. 4 shows three electron guns of a cathode-ray tube according to the invention during their assembly. Three assembly pins 51, 52 and 53 are secured in a block 50. The axes of the pins 51, 52 and 53 are parallel. The diameter of the pins 51, 52 and 53 becomes smaller stepwise towards their ends. In this case also, temporarily provided spacing members 54 are used. After providing all the electrodes, the electrodes which are provided with connection strips not shown are sealed in glass supporting rods by means of said strips. The three electron guns then form one assembly and it is obvious that they can be collectively removed from the assembly pins 51, 52 and 53, said assembly pins remaining secured in the block 50.

COLOUR TELEVISION DISPLAY APPARATUS PROVIDED WITH A PICTURE DISPLAY TUBE WITH ELECTRON BEAMS GENERATED IN ONE PLANE:PHILIPS 20AX SYSTEM INLINE CRT TUBE CONVERGENCE QUADRUPOLE THEORY AND DEVELOPMENT.Colour television display apparatus provided with a display tube with electron beams generated in one plane. In order to enlarge the colour selection angle without the necessity of thickening the neck, a statically energized magnetic quadripolar field is generated at the area of the deflection plane while there is no point of intersection of the beams located within the display tube in the absence of this quadripolar field. This is ensured by four extra windings on the core of the deflection coil system, or by the deflection coils themselves if they are toroidally wound, or by four permanent magnets. The beams may be generated in a diverging manner in the display tube.

1. Colour television display apparatus provided with a picture display tube having a display screen, and with a system of deflection coils comprising a magnetic core for deflecting electron beams into two substantially orthogonal directions, which beams are generated substantially in one plane in the tube, characterized in that the landing spots of the electron beams on the display screen are registered by a statically energized magnetic quadripolar field generated at the area of the deflection plane, while there is no point of intersection of the beams located within the display tube in the absence of said quadripolar field. 2. Television display apparatus as claimed in claim 1, characterized in that the quadripolar field is generated by four extra windings toroidally wound on the core at the area where the deflection directions cross the core and through which a direct current flows. 3. Television display apparatus as claimed in claim 1, characterized in that the quadripolar field is generated by the deflection coils which are toroidally wound on the core, each coil being split up into two halves and a direct current flowing through each coil. 4. Television display apparatus as cliamed in claim 1, characterized in that the quadripolar field is generated by four permanent magnets having pole shoes and being provided on the inner side of the core at the area where the deflection directions cross the core and whose magnetisation is tangentially directed. 5. Television display apparatus as claimed in claim 1, characterized in that the quadripolar field is generated by four extra windings which are wound on the core as saddle coils in directions which are shifted approximately 45° relative to the deflection directions. 6. Television display apparatus as claimed in claim 1, characterized in that the quadripolar field is generated by four permanent magnets having pole shoes and being provided on the inner side of the core at the area where the directions which are shifted approximately 45° relative to the deflection direction cross the core and whose magnetisation is radially directed. 7. Television display apparatus as claimed in claim 1, characterized in that the electron beams are generated in a diverging manner. 8. Television display apparatus as claimed in claim 1, further comprising corrector means for adjusting the direction of the electron beams disposed on the neck of said display tube between the electron beam generating device and said deflection coil system and characterized in that the mutual distance between the electron beams is larger in the deflection plane than at the area of the corrector. 9. An apparatus as claimed in claim 1 comprising a magnetic core on which deflection coils are wound, characterized in that four extra windings are toroidally wound on the core at the area where the deflection directions cross the core. 10. An apparatus as claimed in claim 1 comprising a magnetic core on which deflection coils are wound, characterized in that four permanent magnets having pole shoes are provided on the inner side of the core at the area where the deflection directions cross the core and whose magnetisation is tangentially directed. 11. An apparatus as claimed in claim 1 comprising a magnetic core on which deflection coils are wound, characterized in that four extra windings are wound as saddle coils on the core in directions which are shifted approximately 45° relative to the deflection direction. 12. An apparatus as claimed in claim 1 comprising a magnetic core on which deflection coils are wound, characterized in that four permanent magnets having pole shoes are provided on the inner side of the core at the area where directions which are shifted approximately 45° relative to the deflection directions cross the core and whose magnetisation is radially directed. 13. A device as claimed in claim 1 further comprising means disposed on the neck of said tube between the electron beam generating device and said magnetic core for adjusting the direction of said electron beams. 14. A device for a display tube having a gun for generating a plurality of coplanar electron beams having no intersection point within said tube, said device comprising means disposed on said tube for deflecting said beams substantially at an effective deflection plane, and convergence means disposed on said tube for generating at least a static quadripolar magnetic field substantially at said deflection plane for converging said beams within said tube, whereby a large color selection angle results, thereby minimizing the susceptibility of said beams to interfering fields.

Description:

The invention relates to colour television display apparatus provided with a picture display tube having a display screen, and with a system of deflection coils comprising a magnetic core for deflecting electron beams into two substantially orthogonal directions, which beams are generated substantially in one plane in the tube, and with a corrector for adjusting the direction of the electron beams, said corrector being provided on the neck of the display tube between the generating device of the electron beams and the deflection coil system.

A television display tube of this kind is described, for example, in Netherlands Patent Application No. 7012445. In this tube three electron beams are generated which are located in a substantially horizontal common plane. The neck thereof includes inter alia deflection plates which are present before the position (in the propagation direction of the electrons) where the deflection coil system must be provided externally and before this converging deflection means which are either of the electrostatic or of the magnetic type. The beams can be registered on the display screen by means of these plates and the said means. This is effected both horizontally and vertically so that the said deflection plates and the said means constitute a corrector whereby the direction of the beams is adjusted in order that they converge towards one point on the screen.

However, in a tube of this kind the mutual distance between two beams is much smaller in case of the same cross-section of the neck than in a tube in which the guns are placed on the corners of an equilateral triangle. As a result the so-called colour selection angle is much smaller and therefore the colour purity may be affected by interference fields and/or geometrical deviations. The colour selection angle is understood to mean the smallest angle which is located between two beams in a point on the display screen in the converged condition. An object of the present invention is to increase the mutual distance between the beams at the area of the deflection coil system and therefore also to increase the colour selection angle relative to the known display tubes without changing to a larger cross-section of the neck. To this end the arrangement according to the invention is characterized in that the landing spots of the electron beams on the display screen are also registered by a statically energized magnetic quadripolar field generated at the area of the deflection plane, while there is no point of intersection of the beams located within the display tube in the absence of said quadripolar field.

The deflection plane may be defined in this case as the plane which is at right angles to that in which the electron beams are generated, approximately in the centre of the deflection field generated by the deflection coil system and in which the beams may be considered to be deflected.

Due to the step according to the invention convergence is effected simultaneously with the deflection. It is to be noted that it is known per se from the U.S. Patent Ser. No. 367,944, filed June 7, 1973 to use a magnetic quadripolar field generated at the area of the deflection plane in order to correct deflection errors, which field is generated by means of windings wound on the core. The current flowing through these windings is, however, proportional to the square of at least one deflection current so that the field is not static. A static quadripolar field is known from U.S. Pat. No. 2,907,908, but this field is not generated at the area of the deflection plane.

The invention will be described in detail with reference to the accompanying figures by way of example, and:

FIG. 1 shows a circuit diagram of television display apparatus provided with a display tube in which the electron beams are generated substantially in one plane,

FIG. 2 is a plan view of the paths of the electrons in the display tube of FIG. 1.,

FIGS. 3 and 4 show the system of deflection coils which may be used in the arrangement according to FIG. 1,

FIG. 5 is a principle circuit diagram of an embodiment of the system of deflection coils, and

FIG. 6 shows an enlarged part of FIG. 2.

In FIG. 1, 1 denotes an aerial by which the colour television signal can be received. This colour television signal is applied to an RF and IF amplifier 2 which amplifies and detects the signal and subsequently applies it to a video amplifier 3. This video amplifier 3 applies to a first output 4 the actual video signal consisting of a luminance signal and colour difference signals. These signals are processed in a matrix circuit 5 so that the three colour signals R, G, and B become available at the output of this matrix circuit and are applied to the three cathodes K R , K G and K B of the cathode-ray tube 6 operating as a colour television display tube. The coloured image is displayed on the screen S of tube 6. The synchronizing signal is derived from a second output 7 of video amplifier 3 and this signal is applied to the line deflection generator 8 on the one hand and to the field deflection generator 9 on the other hand. Two outputs 10 and 11 of generator 8 are connected to the deflection coil system 12 at one end and an output 13 is connected to the final anode of display tube 6 at the other end for delivery of the final anode voltage of approximately 25 kilovolts. The outputs 14 and 15 of field deflection generator 9 are likewise connected to deflection coil system 12 for supplying the field deflection current. As a rule, the line deflection current derived from outputs 10 and 11, together with a deflection unit of deflection coil system 12, ensures the horizontal deflection of the electron beams generated by the three cathodes K R , K G and K B . Simultaneously the field deflection current derived from outputs 14 and 15, in co-operation with a further deflection unit of deflection coil system 12, ensures the vertical deflection of the three electron beams. The neck of tube 6 is provided with a corrector 16 to which a direct voltage source 17 applies direct current. A further direct voltage source 18 applies a direct current in a manner to be described hereinafter to deflection coil system 12.

FIG. 2a is a simplified plan view of the paths of the electrons is display tube 6. The electron beams B R , B G and B B for the colours red, green and blue, respectively, are generated by the three cathodes K R , K G and K B and they are modulated in known manner by the colour signals R, G and B. Tube 6 also includes other electrodes which will be left out of consideration for the sake of simplicity. Cathodes K R , K G and K B are arranged in one horizontal plane, in which beam B G substantially coincides with the axis of tube 6 while beams B R and B B are generated in a diverging manner relative thereto. Corrector 16 consists of, for example, four electromagnets 16 RV , 16 BV and 16 RH , 16 BH (not shown) which are substantially located in the same plane as the beams and whose influence is approximately felt in a plane C which is at right angles to the plane of FIG. 2a, in which electromagnets 16 RV and 16 BV ensure the vertical convergence of the "red" and "blue" beams, respectively, while electromagnets 16 RH and 16 BH ensure the horizontal convergence thereof. Corrector 16 envisages a pre-correction of the direction of the beams which can be realized by adjusting the direct currents flowing through the said electromagnets. Beams B R and B B are deflected in the plane C but remain in the horizontal plane. In addition they continue to diverge while beam B G is substantially not influenced.

Without further steps beams B R and B B would continue to diverge in the absence of the deflection currents after passing deflection plane D as is shown in broken lines in FIG. 2a. Beam B G impinges upon display screen S in the centre M thereof. In the presence of the deflection currents flowing through coil system 12 the beams are horizontally and vertically deflected. Beam B G impinges upon screen S at a point P. It is clear that in both cases beams B R and B B will not impinge upon screen S at the same point as beam B G .

FIG. 3 shows an elevational view at right angles to the axis of tube 6 of the magnetic core 19 of deflection coil system 12 in a direction opposite to the propagation direction of the electron beams B R , B G and B B in which the deflection coils themselves have not been shown for the sake of simplicity. Four windings 20, 21, 22 and 23 are toroidally wound on core 19 which are arranged, for example, in series and through which a direct current i provided by direct current source 18 flows. Windings 21 and 23 are provided at the area where the X-axis and core 19 cross each other, which X-axis coincides with the horizontal deflection direction, while windings 20 and 22 are provided at the area where the Y-axis and core 19 cross each other, which Y-axis coincides with the vertical deflection direction. Windings 20, 21, 22 and 23 have substantially the same number of turns and consequently generate four substantially identical magnetic fields some lines of force of which are shown by arrows in FIG. 3. The winding sense of the windings is chosen to be such that the said fields in core 19 counteract each other. Under these circumstances the resultant field can be considered as a quadripolar field whose poles are located approximately in the direction of the diagonals U and V of the X-Y-system of axes. It will be evident that other embodiments are possible for which windings 20, 21, 22 and 23 are not identical and/or through which not the same current flows, provided that the fields generated by these windings result in a quadripolar field as described.

FIG. 3 clearly shows that the quadripolar field in the absence of the deflection field does not exert influence on beam B G which, in fact, is located in the centre of plane D. Beams B B and B R undergo a force directed along the X-axis, which force attempts to bring these beams nearer to each other. Deflection coil system 12 therefore has a converging action. In the presence of the deflection field an influence of beam B G is felt, but this converging action remains.

For a given design of the display tube and of the deflection coil system a fixed direct current through windings 20, 21, 22 and 23 may be chosen for a satisfactorily converged image. The convergence is to be further adjusted by means of corrector 16. For this purpose the currents flowing through electromagnets 16 RV , 16 RH , 16 BV and 16 BH of corrector 16 may be separately adjustable. As a result deviations in the landings of the beams as a result of tolerances of the guns may be largely obviated. Under these circumstances it can be ensured that the three beams impinge at points M and P of display screen S.

FIG. 2b shows the same as FIG. 2a, however, with the difference that beams B R and B B do not diverge after passing plane C, but converge on the understanding, however, that in the absence of the described quadripolar field they would intersect each other beyond the display screen. The advantage of the step according to the invention is then maintained. The same applies when the cathodes are not arranged in a diverging manner but are arranged parallel to each other and to the axis of tube 6. in the latter case, likewise as in the case of FIGS. 2a and 2b, angle α, the colour selection angle, is still larger than in the case where the beams would leave plane C in a converging manner towards a point located within tube 6. In FIG. 2 chain-link lines denote the beams in the known case where the convergence is exclusively effected in plane C.

FIG. 2c shows the situation in which the cathodes run parallel and in which beams B R and B B leave plane C in a diverging manner. In this manner they reach plane D still at a greater distance from the axis than in the known arrangements, in other words, colour selection angle α is enlarged. Since the thickness of the neck of the tube is determined by the largest distance in plane C from the extreme beams, in this case B R and B B , the situation according to FIG. 2c has the advantage that the neck can be made still narrower. As a result both the deflection field and the quadripolar field according to the invention can exert more influence on the beams.

It may be noted that the construction of the guns may be of such a good quality that in the embodiments according to FIGS. 2a and 2b no or substantially no current need be applied to corrector 16. In such a case the quadripolar field according to the invention exclusively or substantially exclusively ensures the convergence of the beams.

It may be concluded from FIG. 3 that the same converging effect may be obtained with the aid of windings 21 and 23 only. This is not true. In fact, the magnetic fields induced in core 19 by windings 21 and 23 would circulate in the core in the absence of windings 20 and 22 without being able to exert a noticeable influence in the space within the core.

The same converging action in deflection plane D may alternatively be realized with the aid of the saddle coils 20', 21', 22', and 23' of FIG. 4 which coils are provided substantially symmetrically about diagonals UU and V. FIG. 4 shows that the lines of force of the quadripolar field generated by these coils have the desired direction in the space within core 19 and close within the core. Alternatively, windings 20, 21, 22 and 23 of FIG. 3 may be replaced by four permanent magnets having pole shoes and being provided on the inner side of core 19 at the area where the X and Y-axis cross the core, the magnetisation of the magnets being tangentially directed. In the same manner windings 20', 21', 22' and 23' of FIG. 4 may be replaced by four permanent magnets having pole shoes and being provided on the inner side of core 19 at the area where diagonals U and V cross the core with the magnetisation of the magnets being radially directed.

In the embodiments already described the deflection coils may be formed arbitrarily, that is to say, it is of no importance for the invention whether they are toroidally wound or are wound as saddle coils. However, in the case where the deflection coils are wound toroidally on core 19 they can generate the required quadripolar field according to one aspect of the invention without the necessity of providing an extra winding on the core. For this purpose each deflection coil must be split up into two coil halves which coil halves are to be arranged on core 19 in the same manner as windings 20, 21, 22 and 23 of FIG. 3. A possible embodiment of this principle is shown in a very diagrammatical way in FIG. 5. In this case windings 20 and 22 are the coil halves for the vertical deflection and are arranged in parallel. In a similar manner windings 21 and 23 are likewise arranged in parallel and are the coil halves for the horizontal deflection. The deflection generators 8 and 9 of FIG. 1 provide the line deflection current i H and the field deflection current i V , respectively. Direct voltage sources 18' and 18" are arranged in series with a coil half, for example, coil halves 21 and 22, respectively. The direct currents i' and i" provided by sources 18' and 18", respectively, are added to deflection currents i H and i V in one coil half, for example, 21 and 20, respectively, while currents i' and i" in the other coil halves 23 and 22 are subtracted from deflection currents i H and i V , respectively. When sources 18' and 18" are proportioned in such a manner that the fields generated by currents i' and i" are substantially equal, coil halves 20, 21, 22 and 23 generate the desired quadripolar field. It will be noted that deflection generators 8 and 9 also provide direct currents for centring the displayed image on screen S. These direct currents are, however, identical for the relevant deflection coil halves 20, 22 and 21, 23 and consequently do not generate a quadripolar field.

In the case where a dynamic correction of the convergence is necessary, it can be performed with the aid of a quadripolar field generated by windings 20, 21, 22 and 23 of FIG. 3 and 5 or windings 20', 21', 22' and 23' of FIG. 4. A line and/or field frequency sawtooth current which is adjustable, if necessary, may be superimposed, for example, on the current provided by the source 18, and sources 18' and 18".

Due to the step according to the invention the colour selection angle is enlarged without the necessity of thickening the cross-section of the neck of the display tube. It may even become narrower. This is an advantage which will now be described in detail.

FIG. 6 shows an enlarged part of FIG. 2 in the vicinity of display screen S in which a shadow mask is denoted by m 1 . Line B R1 denotes the "red" electron beam for known arrangements, line B R2 shows the same beam for the arrangement according to the invention. Beam B G passes through a hole in mask m 1 and impinges upon screen S at a point M G in its centre in which a green luminescing phosphor dot is provided, while beam B R1 passes through a hole in mask m 1 and impinges upon screen S at a point M R in which a red luminescing phosphor dot is provided. Since beam B R2 lands under a larger angle than beam B R1 , it impinges upon screen S at the same point M R if the shadow mask in m 2 is placed nearer to screen S. As a result the landing, that is to say, the colour purity is less sensitive to magnetic interference fields as will now be described. Such fields are generated, for example, by transformers which are present in the television display apparatus or by the earth magnetism field. It is true that the display tube is somewhat screened from such fields but nevertheless they exert a given influence within the tube. As a result the beams of FIG. 6 do not land under the angles shown but under angles which deviate to a slight extent. The landing error then occurring is approximately proportional to the deviation of the angle of the relevant beam caused by the interference fields and to the distance between the shadow mask and the screen. The same applies to the landing errors which may be caused by deviations in the geometry of the different components of the display tube and/or in the position of the deflection plane D with the landing being effected under an angle which deviates to a slight extent. For these reasons it is advantageous to place the mask nearer to the screen.

Although in the foregoing a display tube in which the electron beams are substantially generated in one horizontal plane has been referred to, it will be evident that the invention may alternatively be used if the generating device of the beams is located in a differently directed plane, for example, a vertical plane. A display tube employing three cathodes has also been referred to. The invention is, however, also usable for, for example, multi-beam cathode ray tubes employing one cathode and also for tubes other than those of the shadow mask type.

Pairs of oppositely rotatable ring magnets for a color television display devicePHILIPS 20AX SYSTEM INLINE CRT TUBE.A display device for colour television, comprising a correction device which is to be connected on the neck of a display tube and which comprises two pairs of diametrically magnetized rings in order to enable separate displacement of the electron beams in the tube in the horizontal and in the vertical direction.

1. A display device for colour television, comprising a display tube having a cylindrical neck portion in which three electron guns are adjacently arranged in one plane, and a flared portion, comprising a colour selection electrode and a display screen, the neck portion having provided thereon a correction device comprising a first pair of permanently, diametrically magnetized rings which are rotatable about the tube axis, characterized in that the correction device (13) comprises a second pair (21) of permanently, diametrically magnetized rings which are rotatable about the axis of the tube (1, 3), the fixation of the rings allowing only a rotation of the rings of each pair (19, 21) in opposite directions and through identical angles, the arrangement being such that the resultant magnetic field (H19) of the first ring pair (19) is always perpendicular to the plane of the electron guns (5), the resultant magnetic field (H21) of the second pair (21) always being parallel to this plane. 2. A correction device for a display device as claimed in claim 1, characterized in that the two ring pairs (19, 21) are secured to a common support (29), comprising means for rigidly connecting the correction device (13) to the neck (1) of the tube.

Description:

The invention relates to a display device for colour television, comprising a display tube having a cylindrical neck portion in which three electron guns are adjacently arranged in one plane, and a flared portion, comprising a colour selection electrode and a display screen, the neck portion having provided thereon a correction device comprising a first pair of permanently, diametrically magnetized rings which are rotatable about the tube axis.

A display device of this kind is known, for example, from U.S. Pat. No. 3,725,831. The diametrically magnetized rings serve for the displacement, simultaneously and in the same direction, of the three electron beams generated by the electron guns, so that each of the beams is incident on the display screen only at areas where a phosphor is situated which luminesces in the colour associated with the relevant beam (colour purity adjustment). Because the phosphors on the display screen of a display tube comprising three electron guns which are situated in one plane (usually the horizontal plane) are usually provided in interrupted or non-interrupted stripes perpendicular to the plane of the electron guns (i.e. vertically extending), it is sufficient for the colour purity adjustment per se to displace the electron beams perpendicular to the course of the phosphor stripes, i.e. in the horizontal direction. However, it was found that a deviation of the beams in the vertical direction causes a completely different error, which becomes significant when a pattern comprising horizontal lines is displayed by the display device. In that case the horizontal lines displayed appear to be curved. This curvature can be eliminated by displacing the electron beams together in the vertical direction. It is theoretically possible to realize all combinations of horizontal and vertical displacements using two diametrically magnetized rings. However, it was found in practice that mutual influencing of the two corrections makes it very difficult to perform the two corrections satisfactorily within a reasonable period of time. Therefore, the correction is generally limited to the colour purity, and the correction of the curved horizontal line is omitted.

The invention has for its object to provide a device in which the two corrections can be simply and quickly performed, independently of each other. To this end, the device according to the invention is characterized in that the correction device comprises a second pair of permanently, diametrically magnetized rings which are rotatable about the tube axis, the fixation of the rings allowing only a rotation of the rings of each pair in opposite directions and through identical angles, the arrangement being such that the resultant magnetic field of the first ring pair is always perpendicular to the plane of the electron guns, the resultant magnetic field of the second pair always being parallel to this plane.

The first ring pair then exclusively serves for the adjustment of the colour purity, and the second pair for straightening the curved horizontal line.

The invention will be described in detail hereinafter with reference to the drawing.

FIG. 1 shows a simplified side elevation of a display device according to the invention.

FIGS. 2a and b diagrammatically illustrate the operation of the device according to the invention, and

FIG. 3 shows a section at an increased scale taken along the line III--III of the device shown in FIG. 1.

The colour television display device shown in FIG. 1 comprises a display tube, consisting of a cylindrical neck portion 1 and a flared front portion 3. The neck portion comprises three adjacent electron guns 5 (denoted by broken lines) which are situated in a horizontal plane (perpendicular to the plane of the drawing), whilst the flared portion 3 comprises a colour selection electrode (shadow-mask) 7 and a display screen 9 (also denoted by broken lines). At the area of the transition between the two tube portions a known deflection device 11 is provided about the tube, a correction device 13 being provided therebehind on the tube neck 1. This correction device comprises a pair of convergence rings 15 with permanent four-pole magnetization, a pair of convergence rings 17 with permanent six-pole magnetization, and a first pair of permanently, diametrically magnetized rings 19 (two-pole magnetization) for adjusting the colour purity as described in the said U.S. Pat. No. 3,725,831.

According to the invention, the correction device comprises a second pair of rings 21 with two-pole magnetization which serves for the correction of vertical deviations of the electron beams combined. The resultant magnetic field of the first pair of two-pole rings 19 is always vertically directed, and that of the second pair 21 is always horizontally directed.

This is diagrammatically illustrated in FIGS. 2a and b, in which each time the position of the four poles of a pair of rings is shown with respect to the electron beams 23, 25, 27 generated by the electron guns. FIG. 2a shows that for the ring pair 19 the two north poles N (shown in one plane and on the same circle for the sake of simplicity, even though in reality they are, of course, situated on two different rings) are always situated at the same angular distances α from the vertical, the one north pole being situated to the left and the other north pole being situated to the right of the vertical. The resultant H 19 of the two magnetic field strengths H 19 ' and H 19 " generated by the rings is then also vertically directed, the angle α determining the value of H 19 . This vertical field strength causes a horizontal displacement of the electron beams 23, 25, 27 which is equally large for all beams because the field within the ring pair 19 is substantially homogeneous.

FIG. 2b shows the second ring pair 21, in which the two north poles N enclose equal and opposed angles β with the horizontal, so that the field strength H 21 resulting from the two field strengths H 21 ' and H 21 " is horizontally directed and is dependent only of β as far as its value is concerned. As a result, an equal, vertical displacement of the three electron beams 23, 25, 27 is realized.

FIG. 3 is a cross-sectional view, taken along the line III--III of FIG. 1, of a feasible structural solution for the fixation of the rings of a pair such that the said conditions are satisfied. Connected on the tube neck, using means which are known per se (not shown), is a support 29 which is common to all ring pairs 15, 17, 19, 21, and on which a holder 31 is slid, comprising a recess 33 in which a cam 35 of the support engages so that the holder cannot be rotated with respect to the support and the tube neck. The holder 31 is provided with an annular centring edge 37 with an interruption in which a pinion 41, rotatable about a shaft 39, is situated.

Present within the centring edge 37 is a first diametrically magnetized ring 43 having exterior teeth 45, and situated outside the centring edge is a second diametrically magnetized ring 47 having interior teeth 49. The teeth 45 and 49 engage the pinion 41, with the result that a rotation of the outer ring 47 automatically causes a rotation of the inner ring 43 through the same angle, be it that the latter rotation is in the opposite direction. This construction is described in detail in the previous Netherlands Pat. Application No. 73,04,887 in the name of applicant. So as to facilitate the rotation of the outer ring 47, it is provided with four radial projections 51, one of which is provided with a notch 53 to indicate the location of the north pole N. Mounting is preferably effected such that the north poles N of the two rings 43, 47 are situated directly over the central electron beam 25 when the notch 53 is situated directly over this beam. The other diametrically magnetized ring pair 21 is similarly constructed, be it that the two north poles N are situated in the plane of the three electron beams 23, 25, 27 when they coincide.

Besides the described construction, there are a variety of other possibilities of satisfying the requirements imposed as regards the movement of the two rings, for example, the arrangement of the rings one behind the other with an intermediate pinion, or the coupling of the movement of the rings by means of a belt.

Magnetic correction device for a cathode ray tube:PHILIPS 20AX SYSTEM INLINE CRT TUBE COLOR PURITY NECK MAGNETS DEVICES SYSTEM.Magnetic correction device for a cathode ray tube, which device comprises a plurality of ring pairs which are secured to supports and each consist of rings which have magnetic poles distributed about their peripheries. The two rings of each pair are concentrically mounted and preferably are interconnected by a pinion so as to be rotatable in opposite senses.

1. Magnetic correction device for influencing the paths of electron beams produced in a cathode ray tube, which device comprises at least one support made of a non-magnetic material, securing means for securing the support to the neck of a cathode ray tube, and at least one pair of coaxial rings having magnetic poles distributed about their peripheries, which rings are mounted on the support and are rotatable about their axes in opposite relative directions, characterized in that one of the two rings of a pair has an inner diameter which is greater than the outer diameter of the other ring, the smaller ring being mounted within the larger ring, whilst the outer ring has teeth on its inner periphery and the inner ring has teeth on its outer periphery, at least one pinion, which is rotatable about a spindle secured to the support and extending parallel to the axis of the ring pair, being located in the space between the two rings and meshing with the said teeth. 2. Correction device as claimed in claim 1, characterized in that the teeth on the two rings are equal in number. 3. Correction device as claimed in claim 1, characterized in that the outer ring is provided with at least one radially externally projecting lug. 4. Correction device as claimed in claim 3, characterized in that the support also is provided with at least one radial lug which projects to the exterior. 5. Correction device as claimed in claim 3, characterized in that the lugs are radially extensible by means of an extension adapted to be slipped on one of the lugs. 6. Correction device as claimed in claim 1, characterized in that the securing means for securing the support to the neck of a cathode ray tube comprise an intermediate ring which is adapted to be coaxially placed around the tube neck and to which at least one support is secured so as to be rotatable about the intermediate ring as a spindle. 7. Correction device as claimed in claim 6, characterized in that two supports are provided which are spacedly and axially rotatably secured to the intermediate ring, each of the rings carried by the first support having four magnetic poles distributed about its periphery, whilst each of the rings carried by the second support has six magnetic poles distributed about its periphery. 8. Correction device as claimed in claim 7, characterized in that between the two supports which are rotatably secured to the intermediate ring a third support is secured to the intermediate ring so as to be locked against rotation, each of the rings carried by the third support having two diametrically arranged magnetic poles. 9. Correction device as claimed in claim 6, characterized in that means are provided for locking each support against rotation about the intermediate ring after the desired correction has been effected. 10. Correction device as claimed in claim 9, characterized in that the locking means comprise knurled areas which are provided on each rotatable supports (47) and are capable of engaging a knurled area which is not rotatable relative to the intermediate ring. 11. Correction device as claimed in claim 10, characterized in that the knurled areas are located on the major surfaces of each support and the non-rotatable knurled area is located on the middle, non-rotatable support, thrust means being provided for exerting an axial force on the set of supports. 12. Correction device as claimed in claim 11, characterized in that the thrust means comprise a thrust ring which is secured to the intermediate ring and is rotatable about the intermediate ring as a spindle and the thickness of which varies in the peripheral direction at least near the inner periphery, the portion of varying thickness being located between at least one radial projection formed on the intermediate ring and one of the supports, the arrangement being such that the spacing between the projection and the said support is greater than the smallest thickness and smaller than the greatest thickness of the said portion of the thrust ring. 13. Correction device as claimed in claim 6, characterized in that a conical clamping ring is provided to secure the intermediate ring to the neck of a cathode ray tube.

Description:

The invention relates to a magnetic correction device for influencing the paths of electron beams produced in a cathode ray tube, which device comprises at least one support made of a non-magnetic material, securing means for securing the support on the neck of a cathode ray tube, and at least one pair of coaxial rings having magnetic poles distributed about their peripheries, which rings are mounted on the support and are rotatable about their axes in opposite relative directions.

Such correction devices are used, for example, in colour television display tubes for correcting the paths of the electron beams so that firstly each beam impinges on only that part of a phosphor pattern provided on the display screen of the tube which luminesces in the correct colour (colour purity) and secondly the three beams intersect at the correct location (convergence). Such a device is described, for example, in re-issued U.S. Pat. No. Re. 27,209. A present trend in the design of television receivers is to reduce the receiver depth to a minimum. This depth is substantially exclusively determined by the length of the display tube, one of the factors which govern this length being the axial dimensions of the correction device. Hence it is desirable for this dimension to be as small as possible.

It is an object of the present invention to provide a construction which satisfies this requirement. For this purpose the device according to the invention is characterized in that one of the two rings of a pair has an inner diameter which is greater than the outer diameter of the other ring, the smaller ring being mounted within the larger ring, whilst the outer ring has teeth on its inner periphery and the inner ring has teeth on its outer periphery, at least one pinion which is rotatable about a spindle secured to the support and extending parallel to the axis of the ring pair being located in the space between the two rings and meshing with the said teeth. Preferably the two rings have equal numbers of teeth, causing them to rotate through equal and opposite angles.

For the purpose of corrective adjustment the rings and/or the support preferably have lugs which radially project to the exterior.

An embodiment which enables the correction device to be readily mounted on the tube neck and the support to be readily rotated for adjusting the desired correction is characterized in that the securing means for securing the support on the neck of a cathode ray tube comprise an intermediate ring which is adapted to be coaxially mounted on the tube neck and to which at least one support is secured so as to be rotatable about the intermediate ring as a spindle.

An embodiment of the invention will now be described by way of example with reference to the accompanying diagrammatic drawings, in which:

FIG. 1 is a schematic side elevation of a cathode ray tube provided with a correction device according to the invention,

FIGS. 2a to 2c illustrate the corrections to be effected by means of the correction device according to the invention,

FIG. 3 is a front elevation of a support which carries a pair of rings and forms part of the correction device according to the invention,

FIG. 4 is a longitudinal sectional view of the support and the ring pair shown in FIG. 3,

FIG. 5 is an exploded perspective view of the correction device according to the invention,

FIG. 6 is a side elevation of the correction device shown in FIG. 5,

FIG. 7 is a developed view of a portion of the thrust ring which forms part of the device shown in FIGS. 5 and 6, and

FIGS. 8a and 8b are a longitudinal sectional view and a cross-sectional view respectively of an extension for use with the device shown in FIGS. 5 and 6.

Referring now to FIG. 1, there is schematically shown a cathode ray tube which comprises a cylindrical neck 1 and a flaring part 3 which at the front carries a display screen 5. The neck contains three electron guns 7 which are arranged side by side, only one of them being shown (in broken lines), and are capable of producing three electron beams which extend side by side in a horizontal plane. A known deflection system 9 is provided for deflecting the said electron beams so that they scan the entire display screen 5, which system surrounds the tube at the junction of the neck 1 and the flaring part 3. A magnetic correcting device 11 is mounted on the tube neck for correcting directional errors of the three electron beams produced by the electron guns 7. The corrections to be performed by means of such a device are illustrated in FIGS. 2a to 2c. In these Figures the three electron beams are designated 13, 15 and 17 respectively. The display screen 5 is provided with a pattern of vertical stripes of phosphor which when struck by an electron beam luminesce in one of the colours red, green and blue (not shown). A colour selection electrode (shadow mask) 19 (shown in broken lines in FIG. 1) serves to ensure that each electron beam can impinge on phosphor stripes of one colour only. The beam 13 is to strike the red phosphor, the beam 15 the green phosphor, and the beam 17 the blue phosphor. Owing to inevitable inaccuracies in manufacturing the tube and the deflection system deviations from the ideal situation are found to occur in practice. These deviations will be readily apparent when a grid of horizontal and vertical white lines is displayed on the display screen 5. In actual fact such a grid comprises three exactly registering grids of red, green and blue lines respectively. The first error which may occur consists in that the electron beams do not always impinge on the phosphor stripes of the correct colour only, i.e. part of, for example, the green beam may strike the green phosphor and part may strike the red phosphor. This error can be corrected by shifting the beams in a horizontal direction, for example by producing a magnetic field the lines of force of which extend in the vertical direction at the location of the beams, i.e. centrally of the tube neck 1. This may be effected, for example in the manner shown in FIG. 2a, by means of a magnetic ring 21 having two diametrically opposed magnetic poles. Magnetic lines of force 23 cause horizontal shifting of the beam 15 (and also of the beams 13 and 17) in the direction indicated by arrows 25. The strength of the magnetic field and hence the magnitude of the shift 25 can be rendered controllable by rotating two rings 21 in opposite directions (this step is known). Rotation of both rings through 180° enables the shift to be varied from extreme right via zero to extreme left. This correction is referred to as colour purity correction.

A second possible error is that the three grids (which after the colour purity correction each have the correct colour) are not in register. This error (convergence error) can be corrected in two steps. First (see FIG. 2b) the red and blue grids are made to register by shifting the beams 13 and 17 in opposite directions. For this purpose a quadrupolar magnetic field is produced (in known manner) by means of a magnetic ring 27 which has four poles distributed about its periphery. At the locations of the beams 13 and 17 lines of force 29 of the magnetic field produced by the ring 27 always extend in opposite directions so that shifts 31 and 33 of said beams also have opposite directions. The strength of the quadrupolar field can be controlled, in the same manner as that of the bipolar field of the colour purity ring 21, by rotating two rings 27 in opposite directions. The directions of the shifts 21 and 33 can be controlled by jointly rotating the two rings 27 in the same direction. FIG. 2b shows further that the ring 27 does not produce a magnetic field at the location of the middle beam 15 and hence this beam is not influenced.

After the red and blue grids have been superimposed on one another in the manner described, the resulting combined grid must be brought into register with the green grid. For this purpose the beams 13 and 17 are to be shifted in the same direction through equal distances, as is shown in FIG. 2c. This can be obtained by means of a sextupolar magnetic field which is produced by a magnetic ring 35 having six magnetic poles distributed about its periphery. As FIG. 2c shows, magnetic lines of force 37 then have the same direction at the locations of the beams 13 and 17, so that the shifts 39 and 41 respectively of these beams are identical. In complete analogy with the situation illustrated by FIG. 2b the magnitude and the direction of the shifts are adjustable by rotating the two rings 35 first in opposite senses and then in the same sense. In this case also, the resulting magnetic field strength at the location of the green beam 15 is zero.

From the above it will be obvious that for each possibility of correction a pair of rings having magnetic poles distributed about their peripheries are required which are to be rotatable in opposite senses and, in many cases, jointly in the same sense also. To enable the axial length of the correction device 11 yet to be reduced to a minimum pairs of rings 43, 45 are designed so that one of the rings (43) has an inner diameter which is greater than the outer diameter of the other ring (45). As FIGS. 3 and 4 show, the smaller ring 45 is mounted concentrically within the larger ring 43. The two rings 43 and 45 are disposed on a likewise ring-shaped support 47 which can be mounted on the tube neck so as to be rotatable together with the ring pair about the axis of the tube. The support 47 has a protruding rim 48 along its inner circumference for the purpose of centering the ring pair. In order to enable the two rings 43 and 45 to be rotated in opposite directions also, preferably the outer ring 43 is provided with teeth 49 along its inner periphery whilst the inner ring 45 is provided with teeth 51 along its outer periphery. In the space between the two rings 43 and 45 a pinion 53 is mounted which meshes with both sets of teeth 49 and 51. The pinion 53 is arranged to revolve about a spindle 55 formed on the support 47 and extending parallel to the axis of the ring pair. In order to drive the two rings 43 and 45 the outer ring 43 only has to be rotated, the inner ring 45 then being automatically rotated in the opposite sense. For this purpose the outer ring 43 is provided with radially projecting lugs 57, four in the present embodiment. Adjustment of the magnetic field strength will be easiest if the two rings 43 and 45 always rotate in opposite senses through equal angles. This is obtained by using equal numbers of teeth 49 and 51. If desired, two or more pinions 53 may be used which may be distributed about the space between the two rings 43 and 45. In order to facilitate rotation of the support 47 this also is provided with a number of radially projecting lugs 59 (one in the present case).

A correction device comprising three supports 47 each carrying a ring pair 43, 45 is shown in an exploded perspective view in FIG. 5 and in side elevation in FIG. 6. The three supports 47 are secured one behind the other to an intermediate ring 61 having an inner diameter such as to fit around the tube neck with a small amount of clearance. In order to enable the intermediate ring 61 to be clamped to the tube neck its inner diameter increases towards one end (the righthand end in FIG. 5; this increase is not visible in the drawings), a conical clamping ring 63 fitting within this end. The conical clamping rings 63 has a gap 64 which progressively closes as the ring is axially thrust into the flaring part of the intermediate ring 63. As a result the diameter of the conical clamping ring 63 is decreased so that it firmly encloses the tube neck. To increase the friction between clamping ring 63 and the glass of the tube neck 1 the ring is internally provided with rubber strips 65. To enable axial pressure to be exerted on the clamping ring 63 a ring 67 is provided which by means of radial inward projections 69 engages behind a collar 71 formed on the intermediate ring 61 and has inclined rim sections 73 which cooperate with inclined rim sections 75 of the conical clamping ring 63, so that rotation of the ring 67 results in axial displacement of the clamping ring 63. To facilitate rotation of the ring 67 it is provided with a radially protruding lug 77.

The outer diameter of the intermediate ring 61 is such that it fits with a small amount of clearance in the support 47 and hence can be used as a spindle for rotation of the supports. As has been set out with reference to FIG. 2a, the colour purity correction may in some cases be effected by causing two diametrically magnetised rings to revolve in opposite senses without the need for joint rotation. In this case the support 47 for the colour purity rings may be locked against rotation about the intermediate ring, which may have advantages, as will be set forth hereinafter. For efficient manufacture of the support 47 it is desirable to use supports of a single type only which are capable of being mounted on the intermediate ring 61 so as to be either rotatable or locked. For this purpose the protruding rim 48 along the inner periphery of the support 47 is formed with one or more gaps 79, a corresponding number of projections 81 being formed on the intermediate ring 61. When a support 47 is placed on the intermediate ring 61 so that a projection 81 is received in a gap 79, the support is locked against rotation. The supports 47 which are mounted in front of or behind the projections 81 are freely rotatable. In the embodiment shown in FIGS. 5 and 6 the middle support 47 (which carries diametrically magnetised rings 43 and 45) is locked and is flanked on either side by a rotatable support. One of these rotatable supports carries rings 43 and 45 which each have four magnetic poles distributed about their peripheries for effecting the correction described with reference to FIG. 2b, the other rotatable support carrying rings which each have six poles distributed about their peripheries for performing the correction described with reference to FIG. 2c. Because the locked support is interposed between the two rotatable supports, rotation of one of the rotatable supports is prevented from being transmitted to the other by friction.

Thus the rotary movements of the rotatable supports are entirely independent of one another. To prevent a corrected condition from being incidentally upset, preferably means are provided to lock the supports and possibly the rings against further rotation around the intermediate ring. For this purpose each support 47 is provided on its major surfaces with knurled areas 83 located on raised portions which also serve to center the outer ring 43. When the set of supports 47 is axially compressed, the said knurled areas ensure mutual locking. Because the middle support is locked against rotation by the projection 81, the outer supports also are locked against rotation. Axial compression of the set of supports is performed by means of a thrust ring 85 mounted for rotation around the intermediate ring 61. This thrust ring near its inner periphery has a portion 87 the thickness of which varies the peripheral direction. FIG. 7 shows the developed portion 87. This portion is located between a radial projection 89 formed on the intermediate ring 61 and the left-hand support 47. The various component parts are proportioned so that the projection 89 and the left-hand support 47 are spaced from one another by a distance intermediate between the smallest thickness x and the largest thickness y of the portion 87 of the thrust ring 85. Thus on rotation of the thrust ring 85 the portion 87 acts as a wedge which axially clamps the central supports. To facilitate the said rotation the thrust ring 85 is provided with radially projecting lugs 91. To prevent undue rotation of the thrust ring 85 the portion 87 has a knurled surface 92. In the embodiment shown the support 47 only can be locked against rotation. Obviously the rings 43 and/or 45 may also be provided with knurled areas which can engage corresponding knurled areas on the support 47, enabling the said rings also to be locked. Other locking means may be used, for example a braking block adapted to be forced against the rims of the supports 47 and the outer rings 43, which block and which rims may also be knurled.

When the lugs 57 and 59 of the rings 43 and the support 47 respectively are in substantially equal angular positions, it may be difficult to move one lug by hand without unintentionally moving the other. Hence the said lugs preferably are adapted to be axially extended for example by means of a simple extension 93 which is shown in FIG. 8 and comprises a cavity 95 adapted to be slipped onto the lugs 57, 59 and a handle 97.

In the embodiment described the correction device comprises three supports carrying ring pairs for effecting the corrections described with reference to FIG. 2. Obviously, if desired, a higher or lower number of supports may be used and furthermore the number of magnetic poles of each ring and their distribution about the periphery of each ring may be matched to the respective requirements. Thus, the correction device according to the invention is suitable for solving many different correction problems, also in cathode ray tubes of types different from that shown in FIG. 1 having three electron guns arranged side by side.

For manufacturing the correction device, as far as possible material of low magnetic permeability, for example a synthetic material, is used to prevent the stray field at the rear of the deflection system 9 from influencing the electron beams via the correction device. This also applies to the rings 43, 45, which may be made of a low-permeability magnetic material, as is the case in the embodiment described, or of a synthetic material, in which case magnets of locally secured to them, for example by means of an adhesive.

GLASS FOR TELEVISION DISPLAY CATHODE-RAY TUBES:Glass for envelopes of television display cathode-ray tubes, particularly screen glass for color television, which transmits at most 0.5 mr/h of X-ray radiation at an acceleration voltage of 40 to 45 k. volt, and which has a composition in percent by weight:

what is claimed is

1. Glass for envelopes of television display cathode-ray tubes, particularly intended for the face-plate of the tube, consisting essentially of the following in percent by weight:

2. Glass as claimed in claim 1, consisting essentially of the following in percent by weight:

Description:

The invention relates to glass for an envelope of a television display cathode-ray tube, particularly glass for the face-plate of the tube.

Particular requirements are imposed on glass for envelopes of cathode-ray tubes for the display of colored television images as compared with that for the display of monochrome television images. Such special glasses are known, for example, from the British Pat. specification No. 1,123,857 the composition of which in percent by weight lies within the following range of compositions:

the special requirements which, as compared with glass for the envelopes for monochrome display, are imposed on glass for envelopes for color display, are connected with differences in the manufacture and in the use of these tubes. In the first place, the glass components of envelopes for color display unlike those for the monochrome display envelopes cannot be sealed by fusing them together but must be connected together with the aid of an enamel. This is connected with the fact that a shadow mask is provided in these tubes, which mask determines the path of the required three electron beams. Furthermore, an extremely fine grating-like pattern of three different luminescent substances corresponding to the apertures of the shadow mask is provided on the inner side of the screen. The requirements relative to the maximum permissible distortion of the glass are in this case much more stringent in connection therewith than for glass of envelopes for monochrome display. In addition, the temperature at which the tube must be heated during evacuation and sealing must be approximately 20° higher and the heat treatment is of a longer duration than for the tubes for monochrome display.

The glasses within the above-mentioned range are eminently satisfactory in a technological respect relative to the softening point, the quality and the thermal coefficient of expansion. For the acceleration voltages until recently used on the electron guns, the absorption of these glasses for the X-ray radiation generated during operation as a result of the electron bombardment on the glass and on the shadow mask is sufficiently great. This even applies when the tube is built in in a cabinet in direct vision construction, thus without a protective cover glass.

The requirement up till now had been that the intensity of the transmitted X-ray radiation may be at most 0.5 milliroentgen per hour (mr/h) at a maximum thickness of 11 mm of the screen glass, an acceleration voltage of 27.5 k. volt and an anode current of 300 μA in a television display tube.

There is, however, a tendency to still further increase the margin of safety to X-ray radiation transmitted by television display tubes. There is a need of a kind of glass in which at most 0.5 mr/h is transmitted at an acceleration voltage of 35 k.volt. The above-described glasses then no longer have a sufficiently high absorption and do not satisfy the stricter safety requirements. For reasons of a technological nature, the thickness of the screen cannot be increased much further than 11 mm. To obtain a sufficiently high absorption while using a glass within the above-mentioned range of compositions, the screen should be thicker by as much as 2.5 mm.

For a satisfactory processing of the glass and moulding face-plates thereof, it is necessary that the temperature dependence of the viscosity is not too great. In practice this means that the temperature difference between the softening point, which is the temperature at which the viscosity of the glass is 10 7 6 poises, and the annealing point, which is the temperature at which the viscosity of the glass is 10 13 4 poises, must be at least 190° C.

In connection with the conventio

nal manufacturing technique and the very stringent requirements which are imposed on the maximum permissible distortion of the glass components during manufacture of the tube, it is necessary that glass for a color display tube has an annealing point which is not lower than 485° C.

Finally it is of importance that a glass for a color television display tube has approximately the same coefficient of expansion as that of the known glasses (approximately 99 × 10 -7 between 30° and 300° C.), so that a better match is obtained with the existing glasses and metal components which must be sealed on or in respectively.

In the kind of glass according to the present invention, a content of PbO is present with an approximately equal BaO content relative to the known glass. It is by no means surprising in itself that the absorption of X-ray radiation is increased as a result thereof. It was, however, not obvious that it was possible to maintain the physical properties of the glass at the same level by means of a few other modifications. Furthermore, it is also known (from U. K. Pat. specification No. 664,769) that no discoloration occurs on the glass of the face-plate due to electron bombardment, provided that the glass contains CeO 2 and provided that the glass contains no more than 1 percent of readily reducible oxides. However, the glass according to the invention which does not satisfy the last-mentioned requirement owing to its content of PbO, does not discolor under the influence of the electron bombardment.

The range of glass compositions according to the present invention is characterized by the following limits in percent by weight:

the softening point of these glasses lies between 690° and 710° C.; the annealing point between 485° and 510° C. and the thermal coefficient of expansion is approximately 97 to 100 × 10 -7 between 30° and 300° C. The glasses according to the invention amply satisfy the above-mentioned requirement of transmitting at most 0.5 mr/h at an acceleration voltage of 35 K.volt; it was found that this amount was not yet reached at an acceleration voltage of even 44 to 45 k.volt when using these glasses. The electric resistance 9 is at least 10 9 4 ohm.cm and at least 10 7 5 ohm.cm at 250° and 350°, respectively, while these values are 10 8 5 and 10 6 7 ohm.cm for the above-mentioned known glasses.

The following glass is an example of a glass suitable for the relevant purpose. It is obtained in a manner which is common practice in glass technology by melting the relevant oxides or compounds which are converted into the oxides.

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Resisting the tide of post-modernity may be difficult, but I will attempt it anyway.

Your choice.........Live or DIE.That indeed is where your liberty lies.

IMPORTANT NOTE: - FRANK SHARP obsoletetellyemuseum.blogspot.comwas founded as a public free WEB Museum to all kind of people and amateur and professional CRT TELEVISION Lovers who enjoy using and/or preserving - restoring vintage CRT Televisions sets, or only curious public who was unaware of that kind of technolgy of the past. The purpose is to provide information about vintage Television Receivers Publicy on the WEB that is generally difficult to locate; all this as a important milestone general worldwide reference for the future, globally in the public interest.obsoletetellyemuseum.blogspot.com does not provide support or parts for any apparatus on this site nor do we represent any manufacturer listed on this site in any way. Catalogs, manuals and any other literature that is available on this site is made available for a historical record only. Please remember that safety standards have changed over the years and information in old manuals as well as the old Television receivers themselves may not meet modern standards. It is up to the individual user to use good judgment and to safely operate old machinery. The obsoletetellyemuseum.blogspot.com web site will assume NO responsibilities for damages or injuries resulting from information obtained from this site. No offer to sell or license — Nothing in this site/Blog may be interpreted or construed as an offer to sell products that is open for acceptance or the grant, conveyance or implication of any license under any copyrights, patents or other industrial or intellectual property rights.

Many topics are permanent, so may be updated to any material, for add or correct info.

Sure Fun Times, A working TV Discovered with a CRT Oscilloscope !

Safety Hazards:

------------------------------------------------------Safety Hazards in Radio and TV Repair,------------------------------------------------------

People who believe they can conquer nature are clueless that the laws of nature are a precondition of their existence. Their weapon is a miserable idea.When man attempts to rebel against the iron logic of Nature, he comes into struggle with the principles to which he himself owes his existence as a man. And this attack must lead to his own doom.

Anyone attempting to repair any electronic equipment who does not fully understand the shock hazards, as well as the fire hazards associated with working with electronic equipment, should not attempt such procedures! Improperly attempted repair can kill you and burn down your house.Devices that plug into the wall can produce a very lethal electric shock as well cause a fire from incorrect or careless repairs both during servicing or later on.Improper repair of battery operated devices can also result in bad consequences for you, the device, and any equipment attached to it.

Why some people do repairs themselved then? If you can do the repairs yourself, the equation changes dramatically asyour parts costs will be 1/2 to 1/4 of what a professional will chargeand of course your time is free. The educational aspects may also beappealing. You also will learn a lot in the process.

Consumer electronic equipment like TVs, computer monitors, microwave ovens, and electronic flash units, use voltages at power levels that are potentially lethal. Even more so for industrial equipment like lasers and anything else that is either connected to the power line, or uses or generates high voltage.

Normally, these devices are safely enclosed to prevent accidental contact. However, when troubleshooting, testing, making adjustments, and during repair procedures, the cabinet will likely be open and/or safety interlocks may be defeated. Home-built or modified equipment, despite all warnings and recommendations to the contrary - could exist in this state for extended periods of time - or indefinitely.

Depending on overall conditions and your general state of health, there is a wide variation of voltage, current, and total energy levels that can kill.

Microwave ovens in particular are probably THE most dangerous household appliance to service. There is high voltage - up to 5,000 V or more - at high current - more than an amp may be available momentarily. This is an instantly lethal combination.

TVs and monitors may have up to 35 kV on the CRTbut the current isn't low - like a wrong legend saying a "couple of milliamps" but relatively high because of the boost circuit technology and transformer design. However, the CRT capacitance can hold a painful charge for a long time. In addition, portions of the circuitry of TVs and monitors as well as all other devices that plug into the wall socket are line connected.This is actually even more dangerous than the high voltage due to the greater current available - and a few hundred volts can make you just as dead as 35 kV!

Electronic flash units and strobe lights, and pulsed lasers have large energy storage capacitors which alone can deliver a lethal charge - long after the power has been removed. This applies to some extent even to those little disposable pocket cameras with flash which look so innocent being powered from a single 1.5 V AA battery. Don't be fooled - they are designed without any bleeder so the flash can be ready for use without draining the battery!

Even some portions of apparently harmless devices like VCRs and CD players - or vacuum cleaners and toasters - can be hazardous (though the live parts may be insulated or protected - but don't count on it!

This information also applies when working on other high voltage or line connected devices like Tesla Coils, Jacobs Ladders, plasma spheres, gigawatt lasers, hot and cold fusion generators, cyclotrons and other particle accelerators, as well as other popular hobby type projects. :-)

In addition, read the relevant sections of the document for your particular equipment for additional electrical safety considerations as well as non-electrical hazards like microwave radiation or laser light. Only the most common types of equipment are discussed in the safety guidelines, below.

SAFETY guidelines:

These guidelines are to protect you from potentially deadly electrical shock hazards as well as the equipment from accidental damage.

Note that the danger to you is not only in your body providing a conducting path, particularly through your heart. Any involuntary muscle contractions caused by a shock, while perhaps harmless in themselves, may cause collateral damage. There are likely to be many sharp edges and points inside from various things like stamped sheet metal shields and and the cut ends of component leads on the solder side of printed wiring boards in this type of equipment. In addition, the reflex may result in contact with other electrically live parts and further unfortunate consequences.

The purpose of this set of guidelines is not to frighten you but rather to make you aware of the appropriate precautions. Repair of TVs, monitors, microwave ovens, and other consumer and industrial equipment can be both rewarding and economical. Just be sure that it is also safe!

Don't work alone - in the event of an emergency another person's presence may be essential.

Always keep one hand in your pocket when anywhere around a powered line-connected or high voltage system.

Wear rubber bottom shoes or sneakers. An insulated floor is better than metal or bare concrete but this may be outside of your control. A rubber mat should be an acceptable substitute but a carpet, not matter how thick, may not be a particularly good insulator.

Don't wear any jewelry or other articles that could accidentally contact circuitry and conduct current, or get caught in moving parts.

Set up your work area away from possible grounds that you may accidentally contact.

Have a fire extinguisher rated for electrical fires readily accessible in a location that won't get blocked should something burst into flames.

Use a dust mask when cleaning inside electronic equipment and appliances, particularly TVs, monitors, vacuum cleaners, and other dust collectors.

Know your equipment: TVs and monitors may use parts of the metal chassis as ground return yet the chassis may be electrically live with respect to the earth ground of the AC line. Microwave ovens use the chassis as ground return for the high voltage. In addition, do not assume that the chassis is a suitable ground for your test equipment!

If circuit boards need to be removed from their mountings, put insulating material between the boards and anything they may short to. Hold them in place with string or electrical tape. Prop them up with insulation sticks - plastic or wood.

If you need to probe, solder, or otherwise touch circuits with power off, discharge (across) large power supply filter capacitors with a 2 W or greater resistor of 100 to 500 ohms/V approximate value (e.g., for a 200 V capacitor, use a 20K to 100K ohm resistor). Monitor while discharging and/or verify that there is no residual charge with a suitable voltmeter. In a TV or monitor, if you are removing the high voltage connection to the CRT (to replace the flyback transformer for example) first discharge the CRT contact (under the insulating cup at the end of the fat red wire). Use a 1M to 10M ohm 1W or greater wattage resistor on the end of an insulating stick or the probe of a high voltage meter. Discharge to the metal frame which is connected to the outside of the CRT.

For TVs and monitors in particular, there is the additional danger of CRT implosion - take care not to bang the CRT envelope with your tools. An implosion will scatter shards of glass at high velocity in every direction. There is several tons of force attempting to crush the typical CRT. Always wear eye protection. While the actual chance of a violent implosion is relatively small, why take chances? (However, breaking the relatively fragile neck off the CRT WILL be embarrassing at the very least.)

Connect/disconnect any test leads with the equipment unpowered and unplugged. Use clip leads or solder temporary wires to reach cramped locations or difficult to access locations.

If you must probe live, put electrical tape over all but the last 1/16" of the test probes to avoid the possibility of an accidental short which could cause damage to various components. Clip the reference end of the meter or scope to the appropriate ground return so that you need to only probe with one hand.

Perform as many tests as possible with power off and the equipment unplugged. For example, the semiconductors in the power supply section of a TV or monitor can be tested for short circuits with an ohmmeter.

Provide a reliable means of warning that power is applied and that high voltage filter capacitor(s) still hold a charge during servicing. For example, solder a neon indicator lamp (e.g., an NE2 in series with a 100K ohm resistor) across the line input and a super high brightness LEDs in series with 100K, 1 W resistors across the main filter capacitor(s).

Use an isolation transformer if there is any chance of contacting line connected circuits. A Variac(tm) (variable autotransformer) is not an isolation transformer! However, the combination of a Variac and isolation transformer maintains the safety benefits and is a very versatile device. See the document "Repair Briefs, An Introduction", available at this site, for more details.

The use of a GFCI (Ground Fault Circuit Interrupter) protected outlet is a good idea but may not protect you from shock from many points in a line connected TV or monitor, or the high voltage side of a microwave oven, for example. (Note however, that, a GFCI may nuisance trip at power-on or at other random times due to leakage paths (like your scope probe ground) or the highly capacitive or inductive input characteristics of line powered equipment.) A GFCI is also a relatively complex active device which may not be designed for repeated tripping - you are depending on some action to be taken (and bad things happen if it doesn't!) - unlike the passive nature of an isolation transformer. A fuse or circuit breaker is too slow and insensitive to provide any protection for you or in many cases, your equipment. However, these devices may save your scope probe ground wire should you accidentally connect it to a live chassis.

When handling static sensitive components, an anti-static wrist strap is recommended. However, it should be constructed of high resistance materials with a high resistance path between you and the chassis (greater than 100K ohms). Never use metallic conductors as you would then become an excellent path to ground for line current or risk amputating your hand at the wrist when you accidentally contacted that 1000 A welder supply!

Don't attempt repair work when you are tired. Not only will you be more careless, but your primary diagnostic tool - deductive reasoning - will not be operating at full capacity.

Finally, never assume anything without checking it out for yourself! Don't take shortcuts!

Many people who mistakenly feel that ‘old technology’ is somehow more user-friendly, in some strange way automatically good - merely because it is old. Don’t be fooled! Approach old equipment with an open and alert mind and realise that a hot chassis, or a resistor line cord, or asbestos insulation, or selenium rectifiers require much more thought and consideration for safety.

Live chassis are indiscriminate in whom they kill and even if you are a thoughtful, careful kind of person, that doesn’t mean the last person who handled the set was.

Vintage radio and television receivers use 'live chassis' techniques, in which the chassis is connected directly to one side of the incoming mains supply. This means they can be lethal to carry out repair or servicing work on, unless the appropriate safety measures are in place.

Another thing about live-chassis sets - live spindles. We’ve touched on this already but it’s worth making the point once more. The shafts of switches and potentiometers fixed to the chassis may well be at chassis potential and thus live. The bakelite or wood cabinet is insulated but these shafts are not, and if someone lost the proper grub screw and replaced a knob using a cheesehead screw, the next person to grip that knob may get a dose of 250 volts. Originally these grub screws were sealed and embedded in wax but you cannot rely on subsequent tinkerers having the same high standards.

Even in more orthodox apparatus standards of insulation were not always as high as they are now. Soldered connections to HT and mains wiring should always have rubber or plastic sleeving but in times gone by this was often omitted (or it may since have perished). Beware too of kinked and frayed braiding on cloth-covered mains cords, particularly when the cord has a dropper conductor.

If you are not satisfied that you fully understand the risks involved in this sort of work, do not proceed any further. Instead seek advice and assistance from a competent technician or engineer.

Whenever you acquire a new treasure there's always a terrific temptation to try it out. With mains-driven equipment that means plugging it in and seeing if it works. Well don't, not until you have made some quick checks.

Before contemplating connecting any unknown receiver to the mains supply, spend a little time inspecting it for signs of missing or loose parts, blown fuses, overheating or even fire damage. Use a meter to check obvious points to ensure no short circuit exists (e.g. across the mains input). If you then decide to apply power keep clear but be observant since an elderly electrolytic might explode! This can be avoided if you can apply power gradually through a variac. Auto-transformers are handy for supplying reduced power to sets being repaired but they are not a substitute for a proper isolation transformer!

If you are working with electricity and your work area has a concrete floor, a rubber mat is essential, particularly during damp weather! Where possible try to arrange a neat working area away from water or central heating pipes. For safety try to arrange that this area is separate from the area occupied by your family. This is emphasised because inadvertently rushing to answer a telephone you might just leave a TV chassis connected to a supply and curious little fingers know nothing of the dangers of electricity - or, for that matter - the lethal vacuum encased within every picture tube!

Many younger enthusiasts may not be aware of the dangers of mishandling tubes, in particular the old round types found in early TVs. When handling these tubes eye protection should be worn and tubes must not be left lying around, they must be stored in boxes. The glass is surprising fragile and can implode without any provocation or warning. Bits of glass flying around at high speed can be deadly. The notes following are inspired by Malcolm Burrell again.

Picture tubes are perhaps one of the most hazardous items in any TV receiver. This is because most are of glass construction and contain a very high vacuum. If you measured the total area of glass in any picture tube then estimated the pressure of air upon it at 14.7lb. per square inch, you would discover that the total pressure upon the device could amount to several tons! Fracturing the glass suddenly would result in an extremely rapid implosion such that fragments of glass, metal and toxic chemicals would be scattered over a wide area, probably causing injury to anyone in close proximity. In modern workshops it is now a rule that protective goggles are worn when handling picture tubes.

The weakest point in most picture tubes is where the thin glass neck containing the electron gun is joined to the bowl. It is therefore essential that you refrain from handling the tube by its neck alone. Once a tube is removed from the receiver hold it vertically with the neck uppermost and one hand beneath the screen with the other steadying the device by the neck.With larger devices it is sometimes easier to grip the peripheral of the screen with both hands.

Until the advent of reinforced picture tubes, most were mounted in the cabinet or on the TV chassis by some form of metal band clamped around the face.Never support the weight of the tube by this band since it has been known for the tube to slide out! Some of the larger tubes are extremely heavy. It may, therefore, be easier to enlist assistance.

Before starting to remove a tube, first discharge the final anode connection to the chassis metalwork and preferably connect a shorting lead to this connection whilst you are working. It might be convenient to keep a spare piece of EHT cable with a crocodile clip at one end and a final anode connector at the other.

Exercise care when removing picture tubes from elderly equipment. You may find that the deflection coils have become stuck to the neck. It is extremely dangerous to use a screwdriver prise them away. Gently heating with a hairdryer or soaking in methylated spirit is safer.

Disposal of picture tubes also requires care. Unless rendered safe they should never be placed in dustbins or skips. Many engineers swipe the necks off tubes in cavalier fashion using a broom handle but this is not recommended. A safer method is to make a hole in the side of a stout carton, preferably one designed to hold a picture tube. The tube is placed in the carton and the neck broken using a broom handle. The carton should then be clearly labelled that it contains chemicals and broken glass!

Therefore people who believe they can conquer nature are clueless that the laws of nature are a precondition of their existence. Their weapon is a miserable idea.When man attempts to rebel against the iron logic of Nature, he comes into struggle with the principles to which he himself owes his existence as a man. And this attack must lead to his own doom.

Think for yourself. Otherwise you have to believe what other people tell you.

For most people thinking is a matter of fortune.A society based on individualism is an oxymoron.Freedom is at first the freedom to starve.A wise fool speaks, because he has something to say.A fool speaks, because he has to say something.A wise fool is silent, because there is nothing to say.A fool is silent, because he has nothing to say.

Resist or regretWork for what's good for our people

Help stem the dark tideStand tall or be beat downFight back or die

The man who does not exercise the first law of nature—that of self preservation — is not worthy of living and breathing the breath of life.

We now live in a nation where doctors destroy health, lawyers destroy justice, universities destroy knowledge, governments destroy freedom, the press destroys information, religion destroys morals and our banks destroy the economy.The globalist argument is that if only we erase distinctions, obliterate identities, put everyone on a level playing field, etc.. we can eliminate war and everyone can be so prosperous and efficient, such great cogs in a well-oiled global machine.There will be no more historical grievances because people will no longer even care, they'll have no connection to the past, no foolish pride in past accomplishments of people totally unrelated to them.A globalized culture, no borders, everyone a citizen of the world.Know this: I will never acquiesce to this corrupt, inhuman, Borg-like vision. The dangerous lunatics who push us towards their globalized "utopia" are my enemy. How exactly all this will play out, whether through wars, or whether we can thwart the globalist agenda peacefully (this is my hope of course) I don't know. But I do know that unless people are willing to fight and die, globalism will win out in the end.The actual crimes committed by the EU against the European peoples are directly in violation of the 1948 UN genocide convention, Article II: (c) Deliberately inflicting on the group conditions of life calculated to bring about its physical destruction in whole or in part; (d) Imposing measures intended to prevent births within the group; (e) Forcibly transferring children of the group to another group.* The man who does not exercise the first law of nature—that of self preservation — is not worthy of living and breathing the breath of life.

TELEVISION HISTORY IN BRIEF

Television history

At 1928 Baird transmits from London to New York, using his mechanical system.with 30 vertical lines. By 1930 it was clear that mechanical television systems could never produce the picture quality required for commercial success. For this reason mechanical system was rapidly succeeded by the electronic TV systems. The first all-electronic American systems in 1932 used only 120 scanning lines at 24 frames per second Since the mid-1930s picture repetition frequency (field rate or frame rate) has been the same as the mains frequency, either 50 or 60Hz according to the frequency used in each country. This is for two very good reasons. Studio lighting generally uses alternating current lamps and if these were not synchronised with the field frequency, an unwelcome strobe effect could appear on TV pictures. Secondly, in days gone by, the smoothing of power supply circuits in TV receivers was not as good as it is today and ripple superimposed on the DC could cause visual interference. If the picture was locked to the mains frequency, this interference would at least be static on the screen and thus less obtrusive.To determine what electronic system to use, the BBC sponsored trial broadcasts by two systems, one by Baird, with 240 lines, and one by EMI with 405 lines. Scheduled electronic television broadcasting began in England in 1936 using 405-line system (lasted until the 1980s in the UK). Germany made their forst TV broadcasts at 1936 olympics using 180-line TV system. Germany also made their TV broadcasts by the fall of 1937 using a 441-line system. Also fFrance tested TV (455 line system). RCA introduced electronic television to the U. S. at the 1939 World's Fair,and began regularly scheduled broadcasting at the same time (525 line system).In 1940 the USA established its 525-line standard. At year 1941 the 525-line standard, still in use today in USA, was adopted.Russia also produced TV sets before the war (240 and 343 line systems).World War Two interrupted the development of television. Immediately after World War Two production of TV sets started in the U.S-In USA there was TV broadcasts and few throusand receivers at 1945. In the early 1950s, two competing color TV systems emerged: CBS sequential color (used color wheel) and RCA dot sequential system. At 1953 color broadcasting officially arrives in the U.S. on Dec. 17, when FCC approves modified version of an RCA system.It calls this new RCA color system "NTSC" color. The first NTSC color TVs were on the marker at 1954.In Europe the TV broadcasts started to use experiment using 625 line system 1950s. This standard is used nowadays throughout Europe. France also tried 819 line system at the same time (this system was in use to 1980s). The rest of Europe opted for 625 lines, a system devised in 1946 by two German engineers, M??ller and Urtel (it appears that the Russians came up independently with a very similar system). The use of PAL color standard started at around 1967 and is still in use. The SECAM color system (used in France) testing started also at 1967. The TV broadcasting history has not ended. The newst thign is digital television. It is expected that terrestrial television will open up billion-dollar opportunities for those companies and organisations best prepared to embrace this new broadcasting era. At 1996 small digital satellite dishes hit the market. They become the biggest selling electronic item in history next to the VCR.

Using TV 24H

TV has something for everyone. Idiots, intellectuals, fans of all sorts. Some people are couch potatoes, watch anything just to sit there and be mindless. That's their problem. Children have always needed to be monitored by their parents. If people gotta a mind for it they could figure out the real news even without the internet and there has always been a library.

Is TV bad in and of itself? The researchers aren’t saying that. But we all know that watching television is a solitary, isolating occupation that keeps you sedentary. Sitting in front of the boob tube reduces the time you have available to exercise, interact with your family, read books, and be outdoors. This new research dovetails with other studies, which have linked excessive TV time to obesity and higher rates of cardiovascular disease.

watching too much television can jeopardize your whole family’s health.

This should be a wake-up call to all adults. Stay active. Go outside. Spend time with your spouse and your children with the television off. Read a book and do crossword puzzles to stimulate your imagination and your brain. Reduce your screen time as much as you can.

The National Cancer Institute researchers suggest that watching TV is a public health issue. The price we are paying for our technology-driven lives may be much higher than we previously realized !

DON'T WATCH TV AT ALL !!

The Propaganda TV Machine a.k.a. The Ministry of Truth delivers The Truth from The Government to the people.

At least, that's what they say. In fact, a Propaganda Machine is only employed by The Empire and used to brainwash people into Gullible Lemmings who believe that everything is all right when in fact, it isn't, and that the very people who could help them are their enemies.

Girl Looking TV.

Happy Times:

Do you remember when a telly looked like a real telly? When it was a piece of furniture that you lavished love on, even polished from time to time ?When it was a piece of somewhat at looking in to ?When it was a piece of Highest tech looking inside ? First, this site is a Digital free, HD free, flat panel, HDMI, China, Turks, Afrika free zone. All in all a wealth of vintage information at your finger tips, a one stop unique experience. So step on in, leave the modern throw-away world behind, travel back in time to a vintage world of repair and enjoy.This site has stirred memories about the watching TV's days on a CRT TUBE television......Childhood memories, your parents getting their first colour tv, a b/w or color portable, perhaps memories of renting or buying your first set remote featured, perhaps your days working in the trade, selling or repairing them....... If you enjoyed this site, found its content left you all misty eyed then just talk about it as it would be very welcome............like the time to recover and restore a set ................and happy reminiscing.

Digital TV in Brief.

Digital TV:

Digital television is a hot topic now.If you have looked at television sets at any of the big electronics retailers lately, you know that Digital TV, or DTV, is a BIG deal right now in the U.S. In Europe Digital TV is also a hot topic, because many countries have started terrestrial digital TV broadcasts and plan to end analogue broadcasts after some years (will take 5-10 years). Satellite TV broadcasts have also shifted very much to digital broadcasts.The main advantage if digital broadcasts are that it does not havethe picture quality problems of analogue TVs (it had it's own videoproblems caused by video compression), it allowes putting more TV channels to same medium (TV channel frequencies and satellites) and it allows new services (like HDTV and interactive multimedia). The digital brodcasts are generally designed to use such modulation that the digital data stream (typically around 20-30 Mbit/s) is modulated to the same bandwidth (around 6 MHz) as the analogue TV broadcasts. The used modulation vary between different media, which means thatdifferent modulation techniques are used in terrestrial transmissions, cable TV and satellite. Different modulations are used because of the different characteristics of those transmission medias. There is not on "digital TV", but several different variations of it in use.The basic technology of digital TV, known as MPEG 2 video compressionand MPEG 2 transmission stream format, is same around the world, butis is used somewhat differently in different standards used in differentcountries.

USA uses ACTS Digital Televisio Standard, which standardizes NTSC format transmissions, HDTV transmission, sound formats and data signal modulation in use. The ATSC MPEG-2 formats for DTV, including HDTV, uses 4:2:0 samling for video signal. The US system uses a fixed power and a fixed maximum bitrate, at which some bits are always transmitted. That rate is typically 19.3 Mb/sec.

Europe uses DVB (Digital Video Broadcasting) standard. This standardallows basically normal PAL resolution transmisssion (vasically HDTVcould be added later but is not yet standardized) with several audio formats, digital data rates and digital signal modulation. There are several different variations fo DVB standard for different media:

DVB-T for terrestrial broadcastsDVB-S for satelliteDVB-C for cable TV

Those different DVB versions varyon the data signal modulation methods, error correction and frequency bands used. DVB and option for some interactive extra services, but thestandardization of this is not ready here yet(there are fire different incompatible interactive servicessystems in use in different countries and by different broadcasters).

The process of transmitting digital TV signal is the following: Analog video/audio - digitisation - MPEG compression - Multiplexing ( youcan now call it digital) - Preparation for transmisson - modulation toanalog carrier.Reception process is the following: Demodulation of analogue carrier - Error correction - Demultiplexing - MPEG decompression - DA conversion to get analogue signal (unless you use digital display). The analoguie video signal that gets digitized can be practically from any video source, for example produced with old analogue video production equipment and distributed with a video tape. In high-end system the information is analogue only in the image sensor on the video camera, and from this on the signal gets digitally processed. In many real-life TV production systems the reality is something between those two extremes.

At least in Europe, the signal level requirements for DVB-T are well below the analog requirements, so the transmitter power is much less than on the analog side. In the NorDig recommendation the minimum received signal level for 64QAM, 7/8 code rate with a Rayleigh fading path and 8 dB receiver noise figure would be -64 dBm. With other code rates, modulations and fading mechanisms, the requirement is lower. Many receivers can perform much better at conditions where there is no fading (a quasi error free less than one uncorrected error/hour signal even at 27 dBuV (-82 dBm) with 64QAM and 8 MHz channel width). For analog signals, the recommended level is more than 1 mV (+60 dBuV, -49 dBm). While the ERP can be at least 10 dB lower than analog, the question of power consumption is more complicated, since COFDM with 64QAM carriers require a quite good linearity, which may affect the efficiency and hence power consumption.

Digital TV system in use in USA

The FCC mandate to change our broadcast standards from NTSC analog to ATSC digital broadcasting (DTV) is big bold move, requiring changes in everything from the way the studios shoot video, the format that's transmitted, to the equipment we use to receive and watch broadcastsDTV (digital TV) applies to digital broadcasts in general and to the U.S. ATSC standard in specific. The ATSC standard includes both standard-definition (SD) and high-definition (HD) digital formats. The notation H/DTV is often used to specifically refer to high-definition digital TV. The federal mandate grants the public airwaves to the broadcasters to transmit digital TV in exchange for return of the current analog NTSC spectrum, allowing for a transition period in the interim. At the end of this period scheduled for 2006, broadcasters must be fully converted to the 8VSB broadcast standard. Digital Television ("DTV") is a new broadcast technology that will transform television. The technology of DTV will allows TV broadcasts with movie-quality picture and CD- quality sound and a variety of other enhancements (for example data delivery). With digital television, broadcasters will be able to offer free television of higher resolution and better picture quality than now exists under the current mode of TV transmission. If broadcasters so choose, they can offer what has been called "high definition television" or HDTV, television with theater-quality pictures and CD-quality sound. . Alternatively, a broadcaster can offer several different TV programs at the same time, with pictures and sound quality better than is generally available today. HDTV (high-definition TV) encompasses both analog and digital televisions that have a 16:9 aspect ratio and approximately 5 times the resolution of standard TV (double vertical, double horizontal, wider aspect). High definition is generally defined as any video signal that is at least twice the quality of the current 480i (interlaced) analog broadcast signal. There are 18 approved formats for digital TV broadcasts, but only two (720p/1080i) are proper definition of the term HDTV. The advent of high definition has allowed monitors to read images differently, either in standard interlaced format or progressively. Sets that do not have any decoding capabilities but can display the high-resolution image is often labeled as "HD-Ready" a term that describes 80% or more of the Digital TVs on the market. HDTV displays support digital connections such as HDMI (DVI) and IEEE 1394/FireWire, although standardization is not finished. HDTV in the US is part of the ATSC DTV format. The resolution and frame rates of DTV in the US generally correspond to the ATSC recommendations for SD (640x480 and 704x480 at 24p, 30p, 60p, 60i) and HD (1280x720 at 24p, 20p, and 60p; 1920x1080 at 24p, 30p and 60i). In addition, a broadcaster will be able to simultaneously transmit a variety of other information through a data bitstream to both enhance its TV programs and to provide entirely new services. The technical specifications of USA DTV system is defined in ACTS Digital Television Standards.

Digital TV in Europe

Digital TV brodacasting in Europe is done according to DVB standards. DVB technology has become an integral part of global broadcasting, setting the global standard for satellite, cable and terrestrial transmissions and equipment. There are three versions of DVB in use: DVB-S, DVB-C and DVB-T.DVB-T is a flexible system allowing terrestrial broadcastersto choose from a variety of options to suit their various service environments. This allows the choice between fixed roof-top antenna, portableand even mobile reception of DVB-T services. Broadly speaking the trade-off in one of service bit-rate versus signal robustness.

DVB-T network is very flexible. Having many transmitters all on the same frequency is not a problem for the used COFDM based system. COFDM has been chosen and designed to minimise the effects of multipath in obstructed reception areas. In fact multipath signals can significantly improve the overall received signal with no adverse effects. These properties are particularly valuable for radio cameras and mobile links. DVB-T because of its unique design which allows single frequency networks (SFN). This means that many transmitters along the planned routes can transmit on the same frequency. It is also possible to use simple gap fillers that amplify and retransmit the signal. In-air digital TV broadcasts in Europe use DVB-T. 8 MHz of bandwidth may be used to provide a 24 Mbps digital transmission path using Coded Orthogonal Frequency Division Multiplexing (COFDM) modulation (theoretical maximum 31.67 Mbits for 8 MHz bandwidth). In cases where less bandwidth is available (6 or 7 MHz), the data rate is somewhat lower (around 20 Mbit/s).

DVB-C does the same function as DVB-T, but the modulation used in this system is optimized to operate well in cable TV networks. The modulation used in DVB-C is QAM. Systems from 16-QAM up to 256-QAM can be used, but the system centres on 64-QAM, in which an 8MHz channel can accommodate a physical payload of about 38 Mbit/s. Digital cable TV in Europe uses DVB-C. The DVB standard for the cable return path has been developed jointly with DAVIC, the Digital Audio Visual Council. The specification uses Quadrature Phase Shift Keying (QPSK) modulation in a 200kHz, 1MHz or 2MHz channel to provide a return path for interactive services (from the user to the service provider) of up to about 3Mbit/s. The path to the user may be either in-band (embedded in the MPEG-2 Transport Stream in the DVB-C channel) or out-of-band (on a separate 1 or 2MHz frequency band).

DVB-S is the satellite version of DVB. Satellite transmission has lead the way in delivering digital TV to viewers. Established in 1995, the satellite standard DVB-S is the oldest DVB standard, used on all six major continents. QPSK modulation system is used, with channel coding optimised to the error characteristics of the channel. A typical satellite channel has 36 MHz bandwidth, which may support transmission at up to 38 Mbps (assuming delivery to a 0.5m receiving antenna) using Quadrature Phase Shift Keying (QPSK) modulation. 16 bytes of Reed Solomon (RS) coding are added to each 188 byte transport packet to provide Forward Error Correction (FEC) using a RS(204,188,8) code. For the satellite transmission, the resultant bit stream is then interleaved and convolutional coding is applied.

The core of the DVB digital data stream isthe standard MPEG-2 "data container",which holds the broadcast and service information.This flexible "carry-all" can containanything that can be digitised, includingmultimedia data. The MPEG-2 standards define how to format the various component parts of a multimedia programme (which may consist of: MPEG-2 compressed video, compressed audio, control data and/or user data). It also defines how these components are combined into a single synchronous transmission bit stream. The process of combining the steams is known as multiplexing. The multiplexed stream may be transmitted over a variety of links, standards / products.Each MPEG-2 MPTS multiplex carries a number of streams which in combination deliver the required services. A typical data rate of such multiplex is around 24 Mbps for terrestrial brodcasts.

European DVB systems currently transmit only standard definition TV signals and set top boxes also handle only normal TV resolution. It would be possible to transmit HDTV signals on DVB data stream, but those broadcasts have not yet started in any wide scale. There is one satellite broadcater that broadcasts HDTV DVB signals in Europe (some cable TV operators carry that signal on their cable).

Many DVB-T integrated TV sets, and some set top boxes, in the Europe come with a Common Interface slot - which is pretty much the same form-factor as a PC Card (aka PCMCIA) used in PC laptops. This CI slot accepts a Conditional Access Module, in the same way that DVB-S receivers do, which implements at least one (some can do more than one) decryption algorithm. This CAM may also, itself, have a smart card slot to accept a consumer subscription card to authorise decryption - you plug your smartcard into your CAM and your CAM into the CI slot in your receiver/IDTV. Some DVB receivers have an integrated CAM (in the case of some receivers this is implemented purely in software, with no extra hardware required) rather than a CI slot to plug in a 3rd party device. With these type of receivers you just plug in the smart card and don't have to worry about CI slots and buying CAMs. So there is an interface standard for DVB - but different broadcasters can chose different encryption schemes, requiring different CAMs for decryption.

DVB Standards and related documents are published by the European Telecommunications Standards Institute (ETSI). These include a large number of standards and technical notes to complement the MPEG-2 standards defined by the ISO.

There are few different standard how interactive TV functionaly is implemented in DVB-systems in use in differenct countries. DVB-MHP is one gaining some acceptance. Multimedia Home Platform (MHP) is the open middleware system designed by the DVB Project (www.dvb.org).